Treasury Stock - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended	99 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Mar. 31, 2016	Dec. 31, 2013
Equity Class Of Treasury Stock [Line Items]
Repurchase of common stock (in shares)	470,000		96,277	6,997,849
Average stock price of shares repurchased (in dollars per share)	$ 9.15	$ 17.66		$ 9.26
Repurchase of common stock	$ 4,318,000	$ 1,702,000
Accrued value of repurchase of common stock	300,000
Payments for treasury stock	$ 4,048,000	$ 1,704,000		$ 64,800,000
Remaining number of shares authorized to be repurchased	85,200,000			85,200,000
Maximum
Equity Class Of Treasury Stock [Line Items]
Common stock amount authorized under repurchase program, value (up to)					$ 150,000,000.0