XML 101 R74.htm IDEA: XBRL DOCUMENT v2.4.1.9
Share-Based Payments - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
General vesting period 3 years  
Total unrecognized compensation cost related to unvested share-based payments $ 73,300,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized  
Weighted average period for unrecognized compensation cost expected to be recognized (in years) 1 year 10 months 24 days  
Proceeds from exercise of stock options $ 2,405,000us-gaap_ProceedsFromStockOptionsExercised $ 5,138,000us-gaap_ProceedsFromStockOptionsExercised
Stock Options | Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock option expire from date of grant, period 10 years