Common Stock and Share-Based Compensation - Summary of Restricted Stock Unit Activity (Detail) - RSUs	9 Months Ended
	Sep. 30, 2016 $ / shares shares
PSUs
Outstanding at beginning balance, in shares	966,692
Stock units issued, in shares	489,011
Shares issued upon vesting of stock units, in shares	(231,524)
Stock units canceled or forfeited, in shares	(185,725)
Outstanding at ending balance, in shares	1,038,454
Weighted average grant date fair value | $ / shares	$ 17.18
Employees
PSUs
Outstanding at beginning balance, in shares	871,876
Stock units issued, in shares	445,464
Shares issued upon vesting of stock units, in shares	(176,226)
Stock units canceled or forfeited, in shares	(183,455)
Outstanding at ending balance, in shares	957,659
Weighted average grant date fair value | $ / shares	$ 17.15
Non-Employee Directors
PSUs
Outstanding at beginning balance, in shares	94,816
Stock units issued, in shares	43,547
Shares issued upon vesting of stock units, in shares	(55,298)
Stock units canceled or forfeited, in shares	(2,270)
Outstanding at ending balance, in shares	80,795
Weighted average grant date fair value | $ / shares	$ 17.56