Income Taxes - Computation of Federal Statutory Corporate Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount
Net income before income taxes	$ 11,724	$ 25,865	$ 4,545	$ 6,177	$ 5,123	$ 4,962	$ 2,617	$ 1,930	$ 111,632	$ 48,311	$ 14,632	$ 97,612
Income tax expense (benefit) at federal statutory rate									39,071	16,909	5,121
State income taxes, net of federal income tax benefits									(1,008)	2,507	746
Cancellation of indebtedness income exclusion									(47,080)	0	0
Increase (decrease) in valuation allowance									7,906	(108,899)	(5,806)
Other									1,120	36	(51)
Income tax expense (benefit)	$ 3,103	$ 10,394	$ (102,976)	$ 32	$ 0	$ 0	$ 10	$ 0	$ 9	$ (89,447)	$ 10	$ 9
Effective Income Tax Rate Reconciliation, Percent
Net income before income taxes (as a percent)									100.00%	100.00%	100.00%
Income tax expense (benefit) at federal statutory rate (as a percent)									35.00%	35.00%	35.00%
State income taxes, net of federal income tax benefits (as a percent)									(0.90%)	5.20%	5.10%
Cancellation of indebtedness income exclusion (as a percent)									(42.20%)	(0.00%)	(0.00%)
Increase (decrease) in valuation allowance (as a percent)									7.10%	(225.60%)	(39.70%)
Other (as a percent)									1.00%	0.20%	(0.30%)
Income tax expense (benefit) (as a percent)									0.00%	(185.20%)	0.10%