Computation of net income (loss) per common share ("EPS"), basic and diluted (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Preferred stock dividends	$ (930)	$ (931)	$ (2,792)	$ (2,792)
Preferred Stock Conversions Inducements	0	0	0	0
Net income (loss) applicable to common stock	61,643	228,204	(365,124)	433,504
Weighted Average Number Of Shares Outstanding Basic	102,953,328	102,714,262	102,845,402	102,666,570
Weighted Average Number Diluted Shares Outstanding Adjustment	199,588	303,181	0	348,104
Average common shares outstanding - assuming dilution	103,152,916	103,017,443	102,845,402	103,014,674
Net Income per Common Share - Basic	$ 0.60	$ 2.22	$ (3.55)	$ 4.22
Net Income per Common Share - Diluted	$ 0.60	$ 2.22	$ (3.55)	$ 4.21
Segment, Continuing Operations [Member]
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income (loss) from continuing operations	32,815	225,513	(230,266)	407,640
Net (loss) income from continuing operations - Basic	$ 0.31	$ 2.18	$ (2.27)	$ 3.94
Net (loss) income from continuing operations - Diluted	$ 0.31	$ 2.18	$ (2.27)	$ 3.93
Segment, Discontinued Operations [Member]
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Loss From Discontinued Operations Net Of Tax	$ 29,758	$ 3,622	$ (132,066)	$ 28,656
Net loss from discontinued operations - Basic	$ 0.29	$ 0.04	$ (1.28)	$ 0.28
Net loss from discontinued operations - Diluted	$ 0.29	$ 0.04	$ (1.28)	$ 0.28