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Income Tax Disclosure [Text Block] Note 3 - Net Income Per Common Share - Computation of Basic and Diluted Net Income Per Share (Details) Note 4 - Business Combinations - Allocation of Purchase Price for the Acquisition of Rapid (Details) Net unrealized gains (losses) on investments in securities Note 5 - Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) Expected volatility Note 5 - Goodwill and Other Intangible Assets - Intangible Assets Other Than Goodwill (Details) Current contingent consideration Note 5 - Goodwill and Other Intangible Assets - Estimated Aggregated Amortization Expense (Details) us-gaap_LiabilitiesCurrent Total current liabilities Note 6 - Fair Value Measurements - Fair Value of Financial Assets Measured on a Recurring Basis (Details) Note 7 - Marketable Securities - Short-term and Long-term Available for Sale Securities (Details) Note 7 - Marketable Securities - Balance of Held-to-maturity Debt Securities by Contractual Maturity (Details) Expected life (months) (Month) Expected life (Year) Assets acquired: Note 8 - Inventory - Inventory (Details) us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Note 9 - Stock-based Compensation - Stock Option Activity (Details) Note 9 - Stock-based Compensation - Assumptions Used in the Black-Scholes Option Pricing Model (Details) us-gaap_BusinessCombinationConsiderationTransferred1 Business Combination, Consideration Transferred, Total Total purchase consideration Note 9 - Stock-based Compensation - Restricted Stock Options (Details) Note 9 - Stock-based Compensation - Performance Stock (Details) us-gaap_FinitelivedIntangibleAssetsAcquired1 Finite-lived Intangible Assets Acquired Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] US States and Political Subdivisions Debt Securities [Member] Note 9 - Stock-based Compensation - Assumptions Used in the Valuation of Performance Stock (Details) Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Note 9 - Stock-based Compensation - Assumptions Used to Estimate the Fair Value of the ESPP (Details) Note 10 - Accumulated Other Comprehensive Income (Loss) - Other Comprehensive Loss (Details) Note 12 - Segment Reporting - Revenue From Operations by Reportable Segment (Details) Note 12 - Segment Reporting - Income From Operations (Details) Note 12 - Segment Reporting - Long-lived Assets by Geographic Region (Details) Share-based Payment Arrangement, Option, Activity [Table Text Block] Note 12 - Segment Reporting - Disaggregation of Revenue (Details) Notes To Financial Statements Granted, weighted-average grant date fair value (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue Granted, weighted-average grant date fair value (in dollars per share) Notes To Financial Statements [Abstract] Restrictions lapsed, weighted-average grant date fair value (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue Restrictions lapsed, weighted-average grant date fair value (in dollars per share) Forfeited, weighted-average grant date fair value (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue Forfeited, weighted-average grant date fair value (in dollars per share) Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue Restricted stock, weighted-average grant 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us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod Granted (in shares) Corporate Debt Securities [Member] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod Restrictions lapsed (in shares) Schedule of Nonvested Performance-based Units Activity [Table Text Block] Options exercisable, weighted-average exercise price (in dollars per share) us-gaap_PaymentsToAcquireOtherInvestments Purchases of other assets and investments Options exercisable (in shares) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt Purchases of marketable securities Financial Instruments [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice Options outstanding, weighted-average exercise price (in dollars per share) Options outstanding, weighted-average exercise price (in dollars per share) prlb_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContingentLiabilityCurrent Current contingent consideration The amount of liability arising from an inherited contingency (as defined) which has been recognized as of the acquisition date, classified as current Forfeited, weighted-average exercise price (in dollars per share) Financial Instrument [Axis] Due after one year through five years Goodwill and Intangible Assets Disclosure [Text Block] Schedule of Goodwill [Table Text Block] us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice Granted, weighted-average exercise price (in dollars per share) Exercised, weighted-average exercise price (in dollars per share) prlb_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContingentLiabilityNoncurrent Long-term contingent consideration The amount of liability arising from an inherited contingency (as defined) which has been recognized as of the acquisition date, classified as noncurrent. Accrued compensation Due in one year or less Income taxes payable us-gaap_AccountsPayableCurrent Accounts payable us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber Options outstanding (in shares) Options outstanding (in shares) Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] us-gaap_PolicyTextBlockAbstract Accounting Policies Trade Names [Member] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Employee stock options and other (in shares) us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchases of property, equipment and other capital assets Schedule of Share-based Payment Award, Awards Other Than Stock Options, Valuation Assumptions [Table Text Block] Tabular disclosure of the valuation assumptions of share-based payment awards other than stock options. us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) Noncompete Agreements [Member] Current liabilities Marketing-Related Intangible Assets [Member] Shares used to compute net income per share: us-gaap_Assets Total assets Plan Name [Axis] Plan Name [Domain] Other Products [Member] Represents other products. us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1 Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) Customer Relationships [Member] Investment [Text Block] Computer Software, Intangible Asset [Member] Share-based Payment Arrangement [Text Block] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Award Type [Domain] Performance change, weighted-average grant date fair value (in dollars per share) Represents the weighted average grant date fair value per share in connection to a performance change related to equity instruments other than options. Performance change (in shares) Represents the amount of shares related to a performance change related to equity instruments other than option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Award Type [Axis] Net income Net income us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization Accumulated Amortization Net Total estimated amortization expense Gross Restricted Stock [Member] Performance Shares [Member] Share-based Payment Arrangement, Option [Member] us-gaap_GoodwillForeignCurrencyTranslationGainLoss Foreign currency translation adjustments us-gaap_GoodwillPurchaseAccountingAdjustments Goodwill, Purchase Accounting Adjustments Goodwill acquired during the period Goodwill, Acquired During Period prlb_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentContingentConsideration Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Contingent Consideration This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to contingent consideration in connection with a business combination for which the initial accounting was incomplete. Business Combination Disclosure [Text Block] Property and equipment, net Long-lived assets Goodwill Goodwill Goodwill Goodwill Bank Time Deposits [Member] prlb_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilities Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Tax Liabilities This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to deferred tax liabilities assumed in connection with a business combination for which the initial accounting was incomplete. prlb_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashPaid Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Cash Paid This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to cash paid in connection with a business combination for which the initial accounting was incomplete. Investing activities Marketable securities Fair Value Total marketable securities Amortized Cost Net income per share: Earnings Per Share [Text Block] us-gaap_IncreaseDecreaseInOtherOperatingLiabilities Accrued liabilities and other Income taxes prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingLowerLimit Percentage of Target Number Capable of Being Earned and Vesting, Lower Limit The lower limit percent of target number capable of being earned and vesting at the end of a three-year performance period depending on the company's performance in the final year of the performance period and the award recipient's continued employment. prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingUpperLimit Percentage of Target Number Capable of Being Earned and Vesting, Upper Limit The upper limit percent of target number capable of being earned and vesting at the end of a three-year performance period depending on the company's performance in the final year of the performance period and the award recipient's continued employment. Provision for income taxes Income Tax Expense (Benefit), Total Accounts payable us-gaap_OperatingExpenses Total operating expenses General and administrative Cash and cash equivalents us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss Unrealized Losses Unrealized Gains Employee Stock Purchase Plan [Member] Information pertaining to the Employee Stock Purchase Plan. us-gaap_AllocatedShareBasedCompensationExpense Share-based Payment Arrangement, Expense Amendment Flag Comprehensive Income (net of tax) Comprehensive income City Area Code Common stock, shares outstanding (in shares) Balance (in shares) Balance (in shares) prlb_FinitelivedIntangibleAssetExpectedAmortizationAfterYearFour Thereafter Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Acquired 3D Hubs [Member] Represents acquired 3D Hubs. Current Fiscal Year End Date us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaid expenses and other us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss Realized gain on available-sale-securities Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date Entity File Number Entity Emerging Growth Company Document Type Entity Small Business Entity Shell Company Document Information [Line Items] Document Information [Table] Entity Filer Category Entity Current Reporting Status us-gaap_IncreaseDecreaseInAccountsReceivable Accounts receivable Stock-based compensation expense Entity Tax Identification Number Entity Central Index Key Entity Registrant Name Entity [Domain] Legal Entity [Axis] Entity Address, Address Line One us-gaap_AmortizationOfIntangibleAssets Amortization of Intangible Assets, Total Entity Address, City or Town Entity Address, Postal Zip Code Entity Address, State or Province Long-Term Incentive Plan 2012 [Member] Information pertaining to the 2012 Long-Term Incentive Plan. Entity Common Stock, Shares Outstanding us-gaap_StockRepurchasedAndRetiredDuringPeriodValue Repurchases of common stock us-gaap_StockRepurchasedAndRetiredDuringPeriodShares Repurchases of common stock (in shares) us-gaap_IncreaseDecreaseInInventories Inventories Trading Symbol Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Common shares issued for Hubs acquisition (in shares) Local Phone Number Common shares issued for Hubs acquisition us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised Exercised (in shares) us-gaap_TableTextBlock Notes Tables Common shares issued on exercise of options and other, net of shares withheld for tax obligations Sheet Metal [Member] Represents the information pertaining to sheet metal. Common shares issued on exercise of options and other, net of shares withheld for tax obligations (in shares) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross Granted (in shares) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod Forfeited (in shares) Marketing and sales Fair Value us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and shareholders' equity UNITED STATES Retained earnings Research and development Accumulated other comprehensive loss Money Market Funds [Member] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Changes in operating assets and liabilities: us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_OtherNoncashIncomeExpense Other Inventory Disclosure [Text Block] Long-term operating lease liabilities Schedule of Inventory, Current [Table Text Block] Current operating lease liabilities Other intangible assets, net Current finance lease liabilities Long-term finance lease liabilities Operating lease assets us-gaap_FinanceLeasePrincipalPayments Principal repayments of finance lease obligations Deferred taxes us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear Remaining 2021 Finance lease assets us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo 2023 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree 2024 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour 2025 Debt Securities, Available-for-sale [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths 2022 Other long-term assets us-gaap_ShareBasedCompensation Stock-based compensation expense Weighted average useful life remaining (Year) Useful Life (Year) us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss) Operating expenses us-gaap_AssetsFairValueDisclosure Total us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Amortization of marketable securities Schedule of Finite-Lived Intangible Assets [Table Text Block] us-gaap_LiabilitiesFairValueDisclosure Total Long-term marketable securities Depreciation and amortization Injection Molding (Protomold) [Member] Represents the Injection Molding (Protomold) product. us-gaap_AssetsCurrent Total current assets us-gaap_CashAndCashEquivalentsFairValueDisclosure Cash and cash equivalents 3D Printing (Fineline) [Member] Represents the 3D Printing (Fineline) product. CNC Machining (Firstcut) [Member] Represents the CNC Machining (Firstcut) product. Income taxes receivable Fair value of contingent consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 27,761,063 and 26,776,796 shares as of June 30, 2021 and December 31, 2020, respectively Measurement Frequency [Axis] Adjustments to reconcile net income to net cash provided by operating activities: Measurement Frequency [Domain] Fair Value, Recurring [Member] Common stock, shares authorized (in shares) Common stock, shares issued (in shares) Common stock, par value (in dollars per share) Statistical Measurement [Domain] Maximum [Member] Minimum [Member] Product and Service [Axis] Product and Service [Domain] Statistical Measurement [Axis] Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of June 30, 2021 and December 31, 2020 Preferred stock, shares issued (in shares) Geographical [Axis] Europe Segment [Member] Operating segment for Europe Geographical [Domain] Europe [Member] Preferred stock, shares authorized (in shares) United States Segment [Member] Operating segment for United States. Inventory Inventory, net of allowance Japan Segment [Member] Operating segment for Japan. Preferred stock, par value (in dollars per share) Revenue us-gaap_InventoryValuationReserves Allowance for obsolescence Fair Value, Inputs, Level 3 [Member] Fair Value Hierarchy and NAV [Domain] Total inventory Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value Hierarchy and NAV [Axis] Operating activities Statement [Line Items] Allowance for doubtful accounts Accounts receivable, net of allowance for doubtful accounts of $1,997 and $1,781 as of June 30, 2021 and December 31, 2020, respectively AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Statements of Operations: Short-term marketable securities Additional paid-in capital AOCI Attributable to Parent [Member] Shareholders' equity Other income (loss), net Segment Reporting Disclosure [Text Block] Current assets Fair Value Disclosures [Text Block] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Effect of exchange rate changes on cash and cash equivalents us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Net decrease in cash and cash equivalents us-gaap_Liabilities Total liabilities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash used in financing activities Income from operations Income from operations us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by operating activities Prepaid expenses and other current assets us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash used in investing activities us-gaap_GrossProfit Gross profit Income from Operations by Geographic Area [Table Text Block] Tabular disclosure of income from operations by geographic area. Cost of revenue Consolidation Items [Domain] Long-term deferred tax liabilities Consolidation Items [Axis] us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation Purchases of shares withheld for tax obligations us-gaap_PaymentsForRepurchaseOfCommonStock Repurchases of common stock Scenario [Domain] Forecast [Member] prlb_EffectiveIncomeTaxRateContinuingOperationsIncreaseDecreaseDuringThePeriod Effective Income Tax Rate Continuing Operations Increase (Decrease) During the Period The increase (decrease) during the period in percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Retained Earnings [Member] Scenario [Axis] Proceeds from exercises of stock options Additional Paid-in Capital [Member] Common Stock [Member] Equity Components [Axis] Equity Component [Domain] us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest Income before income taxes Disclosure of Reclassification Amount [Text Block] Disaggregation of Revenue [Table Text Block] Document Quarterly Report Entity Incorporation, State or Country Code us-gaap_UnrecognizedTaxBenefits Unrecognized Tax Benefits, Ending Balance Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Document Transition Report Entity Interactive Data Current Security Exchange Name Title of 12(b) Security Accrued liabilities and other Segments [Axis] Segments [Domain] Diluted (in shares) Diluted - weighted-average shares outstanding: (in shares) Asset Class [Axis] Asset Class [Domain] Statement [Table] Statement of Financial Position [Abstract] Diluted (in dollars per share) Diluted (in dollars per share) Basic (in shares) Basic - weighted-average shares outstanding: (in shares) us-gaap_EffectiveIncomeTaxRateContinuingOperations Effective Income Tax Rate Reconciliation, Percent, Total Business Acquisition [Axis] Basic (in dollars per share) Basic (in dollars per share) Business Acquisition, Acquiree [Domain] Statement of Cash Flows [Abstract] us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High ESPP [Member] ESPP [member Statement of Stockholders' Equity [Abstract] Income Statement [Abstract] us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent Net current-period other comprehensive income (loss) Revenue from External Customers by Geographic Areas [Table Text Block] Contingent consideration Business Combination, Contingent Consideration, Liability, Total Long-lived Assets by Geographic Areas [Table Text Block] Software Platform [Member] Information pertaining to software platform. us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares) prlb_BusinessCombinationRecognizedIdentifiableAssetsAcquiredIncludingGoodwillAndLiabilitiesAssumedAssetsTotal Total assets acquired Amount of assets acquired including goodwill at the acquisition date Investments Classified by Contractual Maturity Date [Table Text Block] us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles Long-term contingent consideration Fair Value, Assets Measured on Recurring Basis [Table Text Block] Financing activities us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Other long-term liabilities us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet Net assets acquired us-gaap_StockholdersEquity Total shareholders' equity Balance Balance us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities Total liabilities assumed Other comprehensive loss us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired Payments to Acquire Businesses, Net of Cash Acquired, Total Net cash consideration Cash used for acquisitions, net of cash acquired us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities Other long-term liabilities us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities Current liabilities Class of Stock [Axis] us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities Long-term deferred tax liabilities us-gaap_CashAcquiredFromAcquisition Cash acquired Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] us-gaap_PaymentsToAcquireBusinessesGross Payments to Acquire Businesses, Gross Comprehensive Income (Loss) [Table Text Block] us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax Unrealized Losses Liabilities assumed: us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax Unrealized Gains us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions Performance stock (in shares) Performance stock (in shares) Operating Segments [Member] us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis Amortized Cost us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets Other long-term assets