Parent Company Only Financial Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS:
Cash and Cash Equivalents, at Carrying Value	$ 299,878				$ 470,599				$ 299,878	$ 470,599	$ 411,583	$ 564,783
Assets	9,236,910				9,193,237				9,236,910	9,193,237	9,493,169
Liabilities and Stockholders' Equity [Abstract]
Junior subordinated debentures	245,294				245,290				245,294	245,290
Interest Payable	4,229				22,575				4,229	22,575
Stockholders' Equity Attributable to Parent	1,217,923				878,557				1,217,923	878,557	770,767	323,249
Liabilities and Equity	9,236,910				9,193,237				9,236,910	9,193,237
Income Statement [Abstract]
Interest expense	18,147	20,683	22,080	23,612	25,520	26,543	27,540	29,494	84,522	109,097	161,106
Net interest income	76,107	75,308	78,910	74,353	71,809	74,836	74,807	73,743	304,678	295,195	284,027
Noninterest expense	89,589	89,408	87,607	88,649	85,875	86,620	91,587	88,308	355,253	352,390	395,045
Income before income taxes	17,745	30,598	32,044	13,291	14,833	11,328	7,555	5,417	93,678	39,133	(224,282)
Income Tax Expense (Benefit)	3,201	0	288,842	0	0	0	0	0	292,043	0	0
Net income	20,946	30,598	320,886	13,291	14,833	11,328	7,555	5,417	385,721	39,133	(224,282)
Statement of Cash Flows [Abstract]
Net cash provided by operating activities									(126,499)	84,072	73,243
Net cash provided by investing activities									1,054,928	378,401	911,985
Proceeds from stock issuance, net									661	0	683,334
Dividends paid									(49,743)	0	0
Net Cash Provided by (Used in) Financing Activities									(1,099,150)	(403,457)	(1,138,428)
Cash and Cash Equivalents, Period Increase (Decrease)									(170,721)	59,016	(153,200)
Parent Company [Member]
ASSETS:
Cash and Cash Equivalents, at Carrying Value	24,443				44,602				24,443	44,602	47,520	24,340
Investments in and Advances to Affiliates, Amount of Equity	1,417,025				1,089,820				1,417,025	1,089,820
Advances to Affiliate	0				283				0	283
Other Assets	20,755				1,158				20,755	1,158
Assets	1,470,530				1,144,048				1,470,530	1,144,048
Liabilities and Stockholders' Equity [Abstract]
Accrued Liabilities, Current	3,072				4,111				3,072	4,111
Junior subordinated debentures	245,294				245,290				245,294	245,290
Interest Payable	4,241				16,090				4,241	16,090
Stockholders' Equity Attributable to Parent	1,217,923				878,557				1,217,923	878,557
Liabilities and Equity	1,470,530				1,144,048				1,470,530	1,144,048
Income Statement [Abstract]
Interest Income, Other									268	300	253
Interest expense									6,785	6,433	6,349
Net interest income									(6,517)	(6,133)	(6,096)
Income (Loss) from Equity Method Investments									380,294	50,961	(206,677)
Noninterest expense									5,385	5,699	11,568
Income before income taxes									368,392	39,129	(224,341)
Income Tax Expense (Benefit)									17,329	4	59
Net income									385,721	39,133	(224,282)
Statement of Cash Flows [Abstract]
Adjustments to reconcile net income to net cash used in operating activities									(412,528)	(42,051)	214,128
Net cash provided by operating activities									(26,807)	(2,918)	(10,154)
Payments to Acquire Interest in Subsidiaries and Affiliates									0	0	(650,000)
Dividends from subsidiaries									52,600	0	0
Net cash provided by investing activities									52,600	0	(650,000)
Proceeds from stock issuance, net									3,791	0	683,334
Dividends paid									(49,743)	0	0
Net Cash Provided by (Used in) Financing Activities									(45,952)	0	683,334
Cash and Cash Equivalents, Period Increase (Decrease)									(20,159)	(2,918)	23,180
Parent Company [Member] | Other Investments [Member]
ASSETS:
Investments in and Advances to Affiliates, Amount of Equity	$ 8,307				$ 8,185				$ 8,307	$ 8,185