Stock-Based Compensation - Schedule of Additional Information on Unvested Options (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining contractual term (in years)	4 years 1 month 10 days	3 years 8 months 19 days
Aggregate intrinsic value	$ 208,152	$ 99,212
Unvested Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	2,789,100	3,070,320
Weighted-average exercise price (per share)	$ 49.47	$ 41.98
Weighted-average remaining contractual term (in years)	5 years 9 months 22 days	5 years 8 months 12 days
Aggregate intrinsic value	$ 80,002	$ 29,740