XML 25 R79.htm IDEA: XBRL DOCUMENT v2.4.1.9
Shareholders' Equity (Share-Based Activity) (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Equity [Abstract]      
Share-based compensation expense $ 10,104us-gaap_AllocatedShareBasedCompensationExpense $ 8,321us-gaap_AllocatedShareBasedCompensationExpense $ 6,692us-gaap_AllocatedShareBasedCompensationExpense
Fair value of shares vested 15,126amsg_FairValueOfSharesVested 11,742amsg_FairValueOfSharesVested 6,425amsg_FairValueOfSharesVested
Cash received from option exercises 2,630us-gaap_ProceedsFromStockOptionsExercised 33,349us-gaap_ProceedsFromStockOptionsExercised 18,214us-gaap_ProceedsFromStockOptionsExercised
Tax benefit from option exercises $ 3,177us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions $ 7,247us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions $ 1,784us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions