Share-Based Compensation - Unrecognized Share-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 40,208
Stock options
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	13,315
Average Expected Recognition Period - in Years	2 years 4 months 19 days
Restricted stock units
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 26,893
Average Expected Recognition Period - in Years	2 years 4 months 19 days