Share-Based Compensation - Unrecognized Share-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 57,015
Stock options
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	18,118
Average Expected Recognition Period - in Years	2 years 9 months 19 days
Restricted stock units
Unrecognized Share Based Compensation Expense [Line Items]
Unrecognized Expense	$ 38,897
Average Expected Recognition Period - in Years	2 years 8 months 8 days