Share-Based Payments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
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	$ 74,300,000
Weighted average period for unrecognized compensation cost expected to be recognized (in years)	1 year 10 months 24 days
Cash received for stock option exercises	$ 5,138,000	$ 57,311,000
Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expire from date of grant, period	10 years