Components of Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	4 Months Ended		8 Months Ended		12 Months Ended
	Dec. 31, 2016		Sep. 12, 2016		Dec. 31, 2015		Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ (5,296)		$ 1,054,602		$ (1,582,961)		$ (409,592)
Less: Preferred stock dividends	0		(5,972)	[1]	(22,789)	[1]	(17,148)	[1]
Induced conversion of preferred stock	0		0		0		(4,256)
Net loss attributable to common shareholders – basic and diluted	$ (5,296)		$ 1,048,630		$ (1,605,750)		$ (430,996)
Weighted-average shares – basic	14,992		88,013		73,639		68,887
Effect of dilutive securities	0	[2]	36,074		0	[2]	0	[2]
Weighted-average shares – diluted	14,992		124,087		73,639		68,887
Potentially dilutive securities with the effect of being anti-dilutive excluded from the calculation of diluted earnings per common share	100				30,200		26,600

[1] Preferred stock dividends were excluded from diluted earnings per share for the years ended December 31, 2015 and 2014, respectively, as the assumed conversion of the outstanding preferred stock would have been anti-dilutive.

[2] For 2015 and 2014, respectively, approximately 30.2 million and 26.6 million potentially dilutive securities, including the Series A and Series B Preferred Stock, stock options and restricted stock units had the effect of being anti-dilutive and were excluded from the calculation of diluted earnings per common share.