Share-Based Compensation - Schedule of Restricted Stock Units to be Settled in Cash (Detail) - shares	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance of Outstanding, Stock Units to be Settled in Cash	1,575,050	[1]	1,842,455		2,288,915
Stock Units to be Settled in Cash, Granted	461,428		873,154	[1]	981,136
Stock Units to be Settled in Cash, Vested	(610,680)		(444,499)		(755,656)
Stock Units to be Settled in Cash, Forfeited	(233,720)		(696,060)		(671,940)
Ending balance of Outstanding, Stock Units to be Settled in Cash	1,192,078		1,575,050	[1]	1,842,455

[1] The total granted awards during 2015 and total outstanding balance as of December 31, 2015 includes an adjustment of 163,566 restricted stock units. These units were previously recorded in the summary table of restricted stock units settled in cash due to the potential for cash settlement upon an involuntary, not for cause termination and are now included in the summary table of restricted stock units settled in stock