XML 20 R70.htm IDEA: XBRL DOCUMENT v2.4.1.9
Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan (RSU and RSAs) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 3,234,230us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]      
Unvested RSUs and RSAs outstanding at December 31, 2012, weighted average grant date fair value (in dollars per share) $ 24.88us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue    
Restricted Stock Units and Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Unvested RSUs and RSAs outstanding at January 1, 2012 (in shares) 1,367,238us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Granted (in shares) 451,136us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Market value share count adjustment for liability awards (in shares) 12,826asgn_ShareBasedCompensationArrangementByShareBasdPaymentAwardEquityInstrumentsOtherThanOptionsMarketValueShareCountAdjustmentForLiabilityAwards
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Vested (in shares) 667,088us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Forfeited (in shares) 51,899us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Unvested RSUs and RSAs outstanding at December 31, 2012 (in shares) 1,086,561us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
1,367,238us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
 
Unvested and expected to vest RSUs and RSAs outstanding at December 31, 2012 (in shares) 965,438asgn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedAndExpectedToVest
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]      
Unvested RSUs and RSAs outstanding at January 1, 2012, weighted average grant date fair value (in dollars per share) $ 18.90us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Granted, weighted average grant date fair value (in dollars per share) $ 33.66us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
$ 26.17us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
$ 16.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
Vested, weighted average grant date fair value (in dollars per share) $ 18.44us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
   
Unvested RSUs and RSAs outstanding at December 31, 2012, weighted average grant date fair value (in dollars per share)   $ 18.90us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember
 
Unvested and expected to vest RSUs and RSAs outstanding at December 31, 2012, weighted average grant date fair value (in dollars per share) $ 25.21asgn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUnvestedAndExpectedToVestWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= asgn_RestrictedStockUnitsAndAwardsMember