Summary of Stock Awards Granted (Detail) - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	[1]	702,067	237,050	2,676,778	1,540,085
Weighted Average Grant Date Fair Value, Stock options	[1]	$ 24.05	$ 16.19	$ 14.67	$ 19.24
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock awards	[2]	65,000		181,783	6,000
Weighted Average Grant Date Fair Value, Restricted stock awards	[2]	$ 33.81		$ 20.80	$ 29.03

[1] A majority of the stock options granted during the periods presented in the table have only service-based criteria and vest over four years.

[2] In September 2015, the Company granted certain employees restricted stock awards (“RSAs”) with performance conditions. If certain performance milestones are achieved within the required time frame, the number of RSAs with performance conditions may be increased from 65,000 to 97,500 shares. As a result, the Company may recognize up to $3.3 million of stock-based compensation related to these grants when performance is deemed probable.