Components of Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net loss		$ (61,980)	$ (80,129)	$ (95,453)	$ (137,294)
Less: Preferred stock dividends	[1]	(2,820)	(6,067)	(5,972)	(12,134)
Net income (loss) attributable to common shareholders, Basic		(64,800)	(86,196)	(101,425)	(149,428)
Net loss attributable to common shareholders, Diluted		$ (64,800)	$ (86,196)	$ (101,425)	$ (149,428)
Weighted-average shares – basic		89,051	72,398	87,496	72,330
Effect of dilutive securities	[2]	0	0	0	0
Weighted-average shares – diluted		89,051	72,398	87,496	72,330
Potentially dilutive securities with the effect of being anti-dilutive excluded from the calculation of diluted earnings per common share				26,600	31,300

[1] Preferred stock dividends were excluded from the computation of diluted earnings (loss) per share for the three and six months ended June 30, 2016 and 2015, as the assumed conversion of the outstanding preferred stock would have been anti-dilutive.

[2] For the six months ended June 30, 2016 and 2015, approximately 26.6 million and 31.3 million, respectively, of potentially dilutive securities, including the Series A Preferred Stock 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 (loss) per common share.