Summary of Stock Awards Granted (Detail) - $ / shares		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	[1]	367,167	117,770	1,974,711	1,303,035
Weighted Average Grant Date Fair Value, Stock options	[1]	$ 15.69	$ 23.68	$ 11.34	$ 19.80
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock awards		110,783		116,783	6,000
Weighted Average Grant Date Fair Value, Restricted stock awards		$ 13.54		$ 13.56	$ 29.03

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