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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net loss		$ (80,129)	$ (100,784)	$ (137,294)	$ (81,559)
Less: Preferred stock dividends	[1]	(6,067)	(1,718)	(12,134)	(3,440)
Induced conversion of preferred stock		0	(3,368)	0	(3,368)
Net income (loss) attributable to common shareholders, Basic		$ (86,196)	$ (105,870)	$ (149,428)	$ (88,367)
Weighted-average shares – basic		72,398	66,514	72,330	66,065
Effect of dilutive securities	[2]	0	0	0	0
Weighted-average shares – diluted		72,398	66,514	72,330	66,065
Potentially dilutive securities with the effect of being anti-dilutive excluded from the calculation of diluted earnings per common share		31,300	18,800	31,500	17,200

[1] Preferred stock dividends were excluded from the computation of diluted earnings per share as the assumed conversion of the outstanding preferred stock would have been anti-dilutive.

[2] For the three and six months ended June 30, 2015, approximately 31.3 million and 31.5 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 per common share. For the three and six months ended June 30, 2014, approximately 18.8 million and 17.2 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 per common share.