Earnings per Common Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings per common share—basic
Net income (loss)	$ (21,153)	$ (86,798)	$ 30,578	$ (52,197)
Less: Preferred stock dividends	1,766	2,414	3,332	7,664
Net income (loss) allocable to common shareholders	(22,919)	(89,212)	27,246	(59,861)
Weighted-average common shares outstanding—basic	72,649	67,162	71,613	65,740
Basic earnings per common share	$ (0.32)	$ (1.33)	$ 0.38	$ (0.91)
Earnings per common share—diluted
Net income (loss)	(21,153)	(86,798)	30,578	(52,197)
Dividends on convertible preferred stock	1,766	2,414	3,332	7,664
Interest on convertible debt, net of tax	0	0	3,673	0
Net income including assumed conversions	$ (22,919)	$ (89,212)	$ 30,919	$ (59,861)
Weighted-average common shares outstanding—basic	72,649	67,162	71,613	65,740
Convertible notes weighted-average shares outstanding	0	0	15,000	0
Options, restricted stock and other dilutive securities	0	0	257	0
Weighted-average common shares outstanding—diluted	72,649	67,162	86,870	65,740
Dilutive earnings per common share	$ (0.32)	$ (1.33)	$ 0.36	$ (0.91)