Stock-based Compensation and Other Employee Benefits - Schedule of Weighted Average Grant Date Fair Value Per Share of Performance-Based and Market-Based RSUs and Assumptions Used to Estimate Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share (in usd per share)	$ 30.93	$ 35.89	$ 43.35
RSUs | Short-term
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share (in usd per share)	$ 28.41	$ 47.18	$ 39.79
Service period (years)	1 year	1 year	1 year
RSUs | Long-term
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share (in usd per share)	$ 33.99	$ 33.43	$ 45.76
Service period (years)	3 years
Market-based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value per share (in usd per share)	$ 22.52
Service period (years)		1 year
Implied volatility			45.00%
Risk-free interest rate			3.10%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Consecutive trading days, vesting threshold	90 days
Maximum | RSUs | Long-term
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period (years)		3 years	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Consecutive trading days, vesting threshold	60 days
Minimum | RSUs | Long-term
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period (years)		2 years	2 years