Stock-based Compensation - Total Stock-Based Compensation Expense Recognized (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expenses	$ 2,782	$ 5,382	$ 12,413	$ 15,492
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expenses	280	1,050	1,401	3,250
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expenses	3,304	2,702	11,269	7,689
Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expenses	$ (802)	$ 1,630	$ (257)	$ 4,553