Quarterly Results of Operations - Summary of Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended							11 Months Ended	12 Months Ended
	Feb. 09, 2018	Mar. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Total revenues	$ 187,273	$ 91,215	$ 164,539	$ 204,658	$ 198,528	$ 200,544	$ 176,644	$ 208,787	$ 245,285	$ 658,940	$ 831,260
Total expenses	133,723	145,659	229,635	252,073	251,736	385,271	303,146	292,595	313,709	879,103	1,294,721
Total other gains (losses)	467,439	484	(11,516)	10,463	12,987	(33,622)	2,824	(8,807)	72,810	12,418	33,205
Income (loss) before income taxes	520,989	(53,960)	(76,612)	(36,952)	(40,221)	(218,349)	(123,678)	(92,615)	4,386	(207,745)	(430,256)
Income tax expense (benefit)	(18)	189	(2,774)	(315)	249	(5,384)	455	1,694	(122)	(2,651)	(3,357)
Net income (loss)	$ 521,007	$ (54,149)	$ (73,838)	$ (36,637)	$ (40,470)	$ (212,965)	$ (124,133)	$ (94,309)	$ 4,508	$ (205,094)	$ (426,899)
Basic earnings (loss) per common and common equivalent share	$ 13.94	$ (12.73)	$ (13.99)	$ (7.28)	$ (8.60)					$ (41.93)	$ (11.61)
Diluted earnings (loss) per common and common equivalent share	$ 13.92	$ (12.73)	$ (13.99)	$ (7.28)	$ (8.60)					$ (41.93)	$ (11.61)
Basic and diluted earnings (loss) per common and common equivalent share						$ (5.70)	$ (3.38)	$ (2.58)	$ 0.12
Reorganization items and fresh start accounting adjustments	$ 464,563	$ (100)		$ (2,600)						$ (2,726)	$ (37,645)
Goodwill and intangible assets impairment	0	$ 10,000	$ 12,700		$ 1,000					23,660	0
Reorganization Items	$ 387,334									$ (2,726)	$ (37,645)