Treasury Stock - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		105 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Nov. 07, 2016	Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items]
Common stock amount authorized under repurchase program, value (up to)							$ 150,000,000.0
Remaining authorized repurchase amount	$ 125,000,000		$ 125,000,000		$ 125,000,000
Repurchase of common stock (in shares)	0	0	1,010,000	96,277	6,997,849
Payments for treasury stock			$ 9,533,000	$ 1,704,000	$ 64,800,000
Average stock price of shares repurchased (in dollars per share)			$ 9.41	$ 17.66	$ 9.26
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Common stock amount authorized under repurchase program, value (up to)						$ 189,800,000.0
Addition to authorized amount						$ 39,800,000.0