Document And Entity Information
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
2021
Expected dividend yield
Note To Financial Statement Details Textual
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
2022
Significant Accounting Policies
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
2023
Note 3 - Net Income Per Common Share
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
2024
Note 4 - Goodwill and Other Intangible Assets
Risk-free interest rate
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]
Note 5 - Fair Value Measurements
Note 6 - Marketable Securities
Note 7 - Inventory
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Remaining 2020
Note 8 - Stock-based Compensation
Note 9 - Accumulated Other Comprehensive Loss
Note 11 - Segment Reporting
prlb_EmployeeStockPurchasePlanOfferingPeriod
Employee Stock Purchase Plan, Offering Period (Month)
The offering period during which employees may purchase stock through the Employee Stock Purchase Plan.
Income Tax Disclosure [Text Block]
Note 3 - Net Income Per Common Share - Computation of Basic and Diluted Net Income Per Share (Details)
Note 4 - Goodwill and Other Intangible Assets - Intangible Assets Other Than Goodwill (Details)
Note 4 - Goodwill and Other Intangible Assets - Estimated Aggregated Amortization Expense (Details)
Expected volatility
Other long-term assets
us-gaap_ShareBasedCompensation
Stock-based compensation expense
Note 5 - Fair Value Measurements - Fair Value of Financial Assets Measured on a Recurring Basis (Details)
Note 6 - Marketable Securities - Short-term and Long-term Marketable Securities (Details)
Weighted average useful life remaining (Year)
us-gaap_LiabilitiesCurrent
Total current liabilities
Note 6 - Marketable Securities - Balance of Held-to-maturity Debt Securities by Contractual Maturity (Details)
Note 7 - Inventory - Inventory (Details)
Useful Life (Year)
Note 8 - Stock-based Compensation - Stock Option Activity (Details)
Note 8 - Stock-based Compensation - Assumptions Used in the Valuation of Options (Details)
Expected life (months) (Year)
Expected life (Year)
Note 8 - Stock-based Compensation - Restricted Stock Options (Details)
Note 8 - Stock-based Compensation - Performance Stock (Details)
Note 8 - Stock-based Compensation - Assumptions Used in the Valuation of Performance Stock (Details)
Note 8 - Stock-based Compensation - Assumptions Used to Estimate the Fair Value of the ESPP (Details)
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 - Accumulated Other Comprehensive Loss - Other Comprehensive Loss (Details)
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
Note 11 - Segment Reporting - Revenue From Operations by Reportable Segment (Details)
Note 11 - Segment Reporting - Income From Operations (Details)
Operating expenses
Note 11 - Segment Reporting - Long-lived Assets by Geographic Region (Details)
Notes To Financial Statements
us-gaap_AssetsFairValueDisclosure
Total
Notes To Financial Statements [Abstract]
Share-based Payment Arrangement, Option, Activity [Table Text Block]
us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments
Amortization of held-to-maturity securities
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)
Proceeds from maturities of marketable securities
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)
Schedule of Finite-Lived Intangible Assets [Table Text Block]
Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Restricted stock, weighted-average grant date fair value (in dollars per share)
Restricted stock, weighted-average grant date fair value (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited (in shares)
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax
Foreign currency translation adjustment
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Restricted stock (in shares)
Restricted stock (in shares)
US Government Agencies Debt Securities [Member]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Granted (in shares)
Corporate Debt Securities [Member]
Long-term marketable securities
Depreciation and amortization
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Restrictions lapsed (in shares)
Schedule of Nonvested Performance-based Units Activity [Table Text Block]
us-gaap_OtherComprehensiveIncomeLossNetOfTax
Net current-period other comprehensive income (loss)
Options exercisable, weighted-average exercise price (in dollars per share)
us-gaap_AssetsCurrent
Total current assets
us-gaap_PaymentsToAcquireOtherInvestments
Purchases of other assets and investments
Other comprehensive income (loss) before reclassifications
Amounts reclassified from accumulated other comprehensive loss
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_PaymentsToAcquireHeldToMaturitySecurities
Purchases of marketable securities
Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 26,648,524 and 26,786,459 shares as of March 31, 2020 and December 31, 2019, respectively
Financial Instruments [Domain]
Adjustments to reconcile net income to net cash provided by operating activities:
Measurement Frequency [Axis]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Options outstanding, weighted-average exercise price (in dollars per share)
Options outstanding, weighted-average exercise price (in dollars per share)
Measurement Frequency [Domain]
Fair Value, Recurring [Member]
Common stock, shares authorized (in shares)
Forfeited, weighted-average exercise price (in dollars per share)
Common stock, shares issued (in shares)
Financial Instrument [Axis]
Common stock, par value (in dollars per share)
Goodwill and Intangible Assets Disclosure [Text Block]
us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Granted, weighted-average exercise price (in dollars per share)
Exercised, weighted-average exercise price (in dollars per share)
Accrued compensation
Income taxes payable
Statistical Measurement [Domain]
Maximum [Member]
Minimum [Member]
us-gaap_AccountsPayableCurrent
Accounts payable
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Options outstanding (in shares)
Options outstanding (in shares)
Statistical Measurement [Axis]
Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of March 31, 2020 and December 31, 2019
Preferred stock, shares issued (in shares)
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Corporate Unallocated and Japan Segment[Member]
Segment for corporate unallocated expenses and Japan.
Europe Segment [Member]
Operating segment for Europe
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)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date
Work in process
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent
Revenue
us-gaap_InventoryValuationReserves
Allowance for obsolescence
Fair Value, Inputs, Level 3 [Member]
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.
Fair Value Hierarchy and NAV [Domain]
us-gaap_InventoryGross
Total inventory
Fair Value, Inputs, Level 1 [Member]
Fair Value, Inputs, Level 2 [Member]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)
Noncompete Agreements [Member]
Fair Value Hierarchy and NAV [Axis]
Current liabilities
Marketing-Related Intangible Assets [Member]
Shares used to compute net income per share:
Raw materials
us-gaap_Assets
Total assets
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total
Operating activities
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)
Customer Relationships [Member]
Investment [Text Block]
Statement [Line Items]
Allowance for doubtful accounts
Accounts receivable, net of allowance for doubtful accounts of $1,821 and $952 as of March 31, 2020 and December 31, 2019, respectively
Computer Software, Intangible Asset [Member]
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Statements of Operations:
Share-based Payment Arrangement [Text Block]
Finite-Lived Intangible Assets by Major Class [Axis]
Finite-Lived Intangible Assets, Major Class Name [Domain]
Short-term marketable securities
Additional paid-in capital
AOCI Attributable to Parent [Member]
Shareholders' equity
Other income, net
Segment Reporting Disclosure [Text Block]
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).
Current assets
Fair Value Disclosures [Text Block]
Award Type [Axis]
Net income
Net income
us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Accumulated Amortization
Net
Total estimated amortization expense
Gross
Restricted Stock [Member]
us-gaap_Liabilities
Total liabilities
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash used in financing activities
Performance Shares [Member]
us-gaap_GoodwillPeriodIncreaseDecrease
Goodwill, Period Increase (Decrease), Total
us-gaap_OperatingIncomeLoss
Income from operations
Income from operations
Share-based Payment Arrangement, Option [Member]
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
Prepaid expenses and other current assets
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash (used in) provided by investing activities
Effect of exchange rate changes on cash and cash equivalents
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Net (decrease) increase in cash and cash equivalents
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
Property and equipment, net
Long-lived assets
Goodwill
Consolidation Items [Axis]
Bank Time Deposits [Member]
us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
Purchases of shares withheld for tax obligations
Investing activities
us-gaap_PaymentsForRepurchaseOfCommonStock
Repurchases of common stock
Amortized Cost
Total marketable securities
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.
Net income per share:
Retained Earnings [Member]
Earnings Per Share [Text Block]
us-gaap_IncreaseDecreaseInOtherOperatingLiabilities
Accrued liabilities and other
Income taxes
Proceeds from exercises of stock options
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.
Additional Paid-in Capital [Member]
Common Stock [Member]
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
Equity Components [Axis]
Equity Component [Domain]
Accounts payable
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Income before income taxes
us-gaap_OperatingExpenses
Total operating expenses
General and administrative
Disclosure of Reclassification Amount [Text Block]
Due in one year or less
Due after one year through five years
Cash and cash equivalents
Cash and cash equivalents, beginning of period
Cash and cash equivalents, end of period
us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Unrealized Losses
Unrealized Gains
us-gaap_AllocatedShareBasedCompensationExpense
Share-based Payment Arrangement, Expense
Money market mutual fund
Document Quarterly Report
Amendment Flag
Entity Incorporation, State or Country Code
us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits, Ending Balance
Accounting Policies [Abstract]
Comprehensive Income (net of tax)
Significant Accounting Policies [Text Block]
Comprehensive income
Document Transition Report
City Area Code
New Accounting Pronouncements, Policy [Policy Text Block]
Entity Interactive Data Current
Security Exchange Name
Common stock, shares outstanding (in shares)
Balance (in shares)
Balance (in shares)
Title of 12(b) Security
Current Fiscal Year End Date
us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
Prepaid expenses and other
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]
Accrued liabilities and other
Entity Filer Category
Entity Current Reporting Status
Segments [Axis]
Segments [Domain]
Diluted (in shares)
Diluted - weighted-average shares outstanding: (in shares)
Debt Securities, Held-to-maturity [Table Text Block]
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]
Statement [Table]
Entity Address, Address Line One
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_AmortizationOfIntangibleAssets
Amortization of Intangible Assets, Total
Entity Address, City or Town
us-gaap_EffectiveIncomeTaxRateContinuingOperations
Effective Income Tax Rate Reconciliation, Percent, Total
Entity Address, Postal Zip Code
Basic (in dollars per share)
Basic (in dollars per share)
Entity Address, State or Province
Statement of Cash Flows [Abstract]
Entity Common Stock, Shares Outstanding
ESPP [Member]
ESPP [member
Statement of Stockholders' Equity [Abstract]
us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Repurchases of common stock
us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Repurchases of common stock (in shares)
Income Statement [Abstract]
Revenue from External Customers by Geographic Areas [Table Text Block]
Long-lived Assets by Geographic Areas [Table Text Block]
us-gaap_IncreaseDecreaseInInventories
Inventories
Trading Symbol
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]
Investments Classified by Contractual Maturity Date [Table Text Block]
Local Phone Number
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
Common shares issued on exercise of options and other, net of shares withheld for tax obligations (in shares)
Fair Value, Assets Measured on Recurring Basis [Table Text Block]
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Granted (in shares)
Financing activities
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Forfeited (in shares)
us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
Other long-term liabilities
Marketing and sales
Fair Value
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and shareholders' equity
Retained earnings
Research and development
Accumulated other comprehensive loss
Cash and Cash Equivalents [Axis]
Cash and Cash Equivalents [Domain]
Changes in operating assets and liabilities:
us-gaap_StockholdersEquity
Total shareholders' equity
Balance
Balance
Other comprehensive income
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]
Class of Stock [Axis]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Comprehensive Income (Loss) [Table Text Block]
Current operating lease liabilities
Other intangible assets, net
us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
Performance stock (in shares)
Performance stock (in shares)
Operating Segments [Member]
Operating lease assets
Deferred taxes
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Thereafter