Earnings per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic earnings (loss) per share:
Net income (loss)	$ (262,146)	$ 84,050	$ (124,168)	$ 242,498
Less preferred stock dividends	(5,481)	(2,070)	(16,441)	(2,070)
Net income (loss) available to common shareholders	(267,627)	81,980	(140,609)	240,428
Weighted average shares	98,318,205	98,233,589	98,656,750	91,296,338
Basic earnings (loss) per share	$ (2.72)	$ 0.83	$ (1.43)	$ 2.63
Diluted earnings (loss) per share:
Net income (loss)	(262,146)	84,050	(124,168)	242,498
Less preferred stock dividends	(5,481)	(2,070)	(16,441)	(2,070)
Net income (loss) available to common shareholders	$ (267,627)	$ 81,980	$ (140,609)	$ 240,428
Weighted average shares	98,318,205	98,233,589	98,656,750	91,296,338
Potential dilutive shares from exercise of stock options
Diluted weighted average shares	98,318,205	98,233,589	98,656,750	91,296,338
Diluted earnings (loss) per share	$ (2.72)	$ 0.83	$ (1.43)	$ 2.63