Allowance for Loan Losses Schedule of Credit Losses Related to Financing Receivables, Current and Non-Current (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	$ 9,946	$ 14,061
Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	6,150	7,239	5,004
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	92,693	96,610	93,938
Financing Receivable, Allowance for Credit Losses	98,843	103,849	98,942	107,699
Financing Receivable, Individually Evaluated for Impairment	98,333	105,157	96,371
Financing Receivable, Collectively Evaluated for Impairment	8,681,637	7,758,052	8,635,288
Financing Receivable, Net	8,779,970	7,863,209	8,731,659
Financing Receivable, Allowance for Credit Losses, Write-downs	(10,776)	(17,417)
Financing Receivable, Allowance for Credit Losses, Recovery	4,869	5,438
Provision for Loan, Lease, and Other Losses	5,808	8,129
Noncovered Loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,957	972	577
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	38,470	36,200	35,632
Financing Receivable, Allowance for Credit Losses	40,427	37,172	36,209	32,363
Financing Receivable, Individually Evaluated for Impairment	8,445	6,079	6,187
Financing Receivable, Collectively Evaluated for Impairment	3,374,178	2,884,646	3,300,339
Financing Receivable, Net	3,382,623	2,890,725	3,306,526
Financing Receivable, Allowance for Credit Losses, Write-downs	(2,103)	(6,292)
Financing Receivable, Allowance for Credit Losses, Recovery	1,055	350
Provision for Loan, Lease, and Other Losses	5,266	10,751
Noncovered Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	769	2,478	913
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	17,630	25,300	19,213
Financing Receivable, Allowance for Credit Losses	18,399	27,778	20,126	31,857
Financing Receivable, Individually Evaluated for Impairment	24,160	32,112	24,007
Financing Receivable, Collectively Evaluated for Impairment	2,170,829	2,011,499	2,200,409
Financing Receivable, Net	2,194,989	2,043,611	2,224,416
Financing Receivable, Allowance for Credit Losses, Write-downs	(53)	(669)
Financing Receivable, Allowance for Credit Losses, Recovery	132	81
Provision for Loan, Lease, and Other Losses	(1,806)	(3,491)
Noncovered Loans [Member] | Commercial Construction Financing Receivable Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	90	224	105
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,651	4,900	3,716
Financing Receivable, Allowance for Credit Losses	2,741	5,124	3,821	5,173
Financing Receivable, Individually Evaluated for Impairment	2,779	8,929	3,405
Financing Receivable, Collectively Evaluated for Impairment	307,946	276,786	332,142
Financing Receivable, Net	310,725	285,715	335,547
Financing Receivable, Allowance for Credit Losses, Write-downs	(516)	(38)
Financing Receivable, Allowance for Credit Losses, Recovery	58	263
Provision for Loan, Lease, and Other Losses	(622)	(274)
Noncovered Loans [Member] | Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0	0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,129	334	639
Financing Receivable, Allowance for Credit Losses	1,129	334	639	341
Financing Receivable, Individually Evaluated for Impairment	0	0	0
Financing Receivable, Collectively Evaluated for Impairment	164,137	74,112	139,236
Financing Receivable, Net	164,137	74,112	139,236
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Financing Receivable, Allowance for Credit Losses, Recovery	89	37
Provision for Loan, Lease, and Other Losses	401	(44)
Noncovered Loans [Member] | Installment Financing Receivable Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,458	1,902	1,526
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	7,693	12,851	9,628
Financing Receivable, Allowance for Credit Losses	9,151	14,753	11,154	17,981
Financing Receivable, Individually Evaluated for Impairment	31,117	32,378	30,870
Financing Receivable, Collectively Evaluated for Impairment	1,291,678	1,227,552	1,297,388
Financing Receivable, Net	1,322,795	1,259,930	1,328,258
Financing Receivable, Allowance for Credit Losses, Write-downs	(4,594)	(5,238)
Financing Receivable, Allowance for Credit Losses, Recovery	2,496	3,202
Provision for Loan, Lease, and Other Losses	95	(1,192)
Noncovered Loans [Member] | Home Equity Receivable Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	89	66	34
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	14,479	6,203	13,690
Financing Receivable, Allowance for Credit Losses	14,568	6,269	13,724	6,766
Financing Receivable, Individually Evaluated for Impairment	6,917	5,522	6,281
Financing Receivable, Collectively Evaluated for Impairment	805,541	734,025	799,797
Financing Receivable, Net	812,458	739,547	806,078
Financing Receivable, Allowance for Credit Losses, Write-downs	(1,837)	(2,735)
Financing Receivable, Allowance for Credit Losses, Recovery	483	840
Provision for Loan, Lease, and Other Losses	2,198	1,398
Noncovered Loans [Member] | Credit Card Receivables Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	74	92	127
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	6,995	6,428	7,257
Financing Receivable, Allowance for Credit Losses	7,069	6,520	7,384	7,369
Financing Receivable, Individually Evaluated for Impairment	1,388	2,060	1,612
Financing Receivable, Collectively Evaluated for Impairment	139,333	138,558	144,775
Financing Receivable, Net	140,721	140,618	146,387
Financing Receivable, Allowance for Credit Losses, Write-downs	(1,403)	(1,583)
Financing Receivable, Allowance for Credit Losses, Recovery	513	630
Provision for Loan, Lease, and Other Losses	575	104
Noncovered Loans [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,713	1,505	1,722
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3,646	4,394	4,163
Financing Receivable, Allowance for Credit Losses	5,359	5,899	5,885	5,849
Financing Receivable, Individually Evaluated for Impairment	23,527	18,077	24,009
Financing Receivable, Collectively Evaluated for Impairment	427,995	410,874	421,202
Financing Receivable, Net	451,522	428,951	445,211
Financing Receivable, Allowance for Credit Losses, Write-downs	(270)	(862)
Financing Receivable, Allowance for Credit Losses, Recovery	43	35
Provision for Loan, Lease, and Other Losses	$ (299)	$ 877