Summary of Quarterly Financial Data (Unaudited) (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data [Abstract]
Interest income	$ 233,258,000		$ 233,852,000		$ 231,513,000		$ 230,391,000		$ 240,000,000		$ 247,676,000		$ 253,809,000		$ 262,654,000		$ 929,014,000	$ 1,004,140,000	$ 1,141,756,000
Net interest income	204,331,000		203,970,000		202,077,000		199,814,000		207,456,000		212,345,000		213,356,000		220,959,000		810,192,000	854,117,000	924,154,000
Provision for loan losses	14,064,000		6,761,000		13,077,000		35,696,000		146,526,000		63,572,000		44,222,000		66,049,000		69,598,000	320,369,000	418,795,000
Income (loss) before income taxes	59,710,000		73,459,000		72,906,000		46,553,000		(72,299,000)		30,514,000		37,347,000		35,916,000		252,628,000	31,477,000	(59,532,000)
Income tax expense (benefit)	21,130,000		27,765,000		27,371,000		16,979,000		(796,339,000)		(211,000)		(2,105,000)		(77,000)		93,245,000	(798,732,000)	1,312,000
Net income (loss)	38,580,000	[1]	45,694,000	[1]	45,535,000	[1]	29,574,000	[1]	724,040,000	[2]	30,725,000	[2]	39,452,000	[2]	35,993,000	[2]	159,383,000	830,209,000	(60,844,000)
Net income (loss) attributable to common shareholders	35,850,000	[1]	37,188,000	[1]	30,717,000	[1]	14,798,000	[1]	709,304,000	[2]	16,030,000	[2]	24,803,000	[2]	21,369,000	[2]	118,553,000	771,506,000	(118,712,000)
Basic earnings per common share:
Net income (loss) attributable to common shareholders (per share)	$ 0.04		$ 0.04		$ 0.04		$ 0.02		$ 0.90		$ 0.02		$ 0.03		$ 0.03
Net loss attributable to common shareholders (per share)																	$ 0.13	$ 0.98	$ (0.15)
Diluted earnings per common share:
Net income (loss) attributable to common shareholders (per share)	$ 0.04		$ 0.04		$ 0.03		$ 0.02
Net loss attributable to common shareholders (per share)									$ 0.78		$ 0.02		$ 0.03		$ 0.02		$ 0.13	$ 0.85	$ (0.15)
Litigation loss contingency expense	10,000,000
Valuation allowance for deferred tax assets	$ 796,300,000																$ 4,083,000	$ 802,771,000	$ (31,844,000)

[1] The fourth quarter of 2013 results include litigation loss contingency expense of $10.0 million

[2] The fourth quarter of 2012 results reflect a $796.3 million income tax benefit due primarily to the reversal of substantially all of the deferred tax asset valuation allowance. For additional discussion of the valuation allowance for deferred tax assets, see "Part II - Item 8. Financial Statements and Supplementary Data - Note 24 - Income Taxes" of this Report.