Share-Based Compensation - Schedule of Fair Value, Liabilities Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - Multi-year Outperformance Plan [Member] $ in Thousands	Dec. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
OPP	$ 5,457
Significant Unobservable Inputs Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
OPP	$ 5,457