Allowance for Loan Losses Troubled Debt Restructuring on Financing Receivables (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2,885		2,842		2,444
Financing Receivable, Modifications, Recorded Investment	$ 147,031	[1]	$ 150,487	[1]	$ 151,326	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	191,735	[1]	202,273	[1]	190,805	[1]
Noncovered Loans Commercial [Member] | Commercial and Industrial Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	25		24		15
Financing Receivable, Modifications, Recorded Investment	2,627	[1]	2,617	[1]	3,388	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	7,864	[1]	8,044	[1]	6,031	[1]
Noncovered Loans Commercial [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	45		40		30
Financing Receivable, Modifications, Recorded Investment	17,217	[1]	16,305	[1]	9,136	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	22,187	[1]	20,701	[1]	12,745	[1]
Noncovered Loans Commercial [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	31		28		27
Financing Receivable, Modifications, Recorded Investment	2,779	[1]	2,955	[1]	4,593	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	3,266	[1]	3,419	[1]	5,250	[1]
Noncovered Loans Commercial [Member] | Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	101		92		72
Financing Receivable, Modifications, Recorded Investment	22,623	[1]	21,877	[1]	17,117	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	33,317	[1]	32,164	[1]	24,026	[1]
Noncovered Consumer Loans [Member] | Consumer Installment Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1,840		1,769		1,506
Financing Receivable, Modifications, Recorded Investment	31,117	[1]	30,870	[1]	32,378	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	32,635	[1]	32,653	[1]	32,378	[1]
Noncovered Consumer Loans [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	238		226		184
Financing Receivable, Modifications, Recorded Investment	6,917	[1]	6,281	[1]	5,522	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	7,247	[1]	6,488	[1]	5,522	[1]
Noncovered Consumer Loans [Member] | Consumer Credit Card Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	343		389		454
Financing Receivable, Modifications, Recorded Investment	1,388	[1]	1,612	[1]	2,060	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	1,388	[1]	1,612	[1]	2,060	[1]
Noncovered Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	294		298		184
Financing Receivable, Modifications, Recorded Investment	23,527	[1]	24,009	[1]	18,076	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	26,118	[1]	26,662	[1]	18,076	[1]
Noncovered Consumer Loans [Member] | Consumer Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2,715		2,682		2,328
Financing Receivable, Modifications, Recorded Investment	62,949	[1]	62,772	[1]	58,036	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	67,388	[1]	67,415	[1]	58,036	[1]
Noncovered Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2,816		2,774		2,400
Financing Receivable, Modifications, Recorded Investment	85,572	[1]	84,649	[1]	75,153	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	100,705	[1]	99,579	[1]	82,062	[1]
Covered Loans Commercial [Member] | Commercial and Industrial Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	3		3		12
Financing Receivable, Modifications, Recorded Investment	1,723	[1]	1,763	[1]	7,662	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	1,958	[1]	1,998	[1]	14,877	[1]
Covered Loans Commercial [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	20		20		23
Financing Receivable, Modifications, Recorded Investment	48,327	[1]	50,272	[1]	54,824	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	57,426	[1]	57,483	[1]	60,075	[1]
Covered Loans Commercial [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	10		10		9
Financing Receivable, Modifications, Recorded Investment	6,296	[1]	8,171	[1]	13,687	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	26,502	[1]	37,547	[1]	33,791	[1]
Covered Loans Commercial [Member] | Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	33		33		44
Financing Receivable, Modifications, Recorded Investment	56,346	[1]	60,206	[1]	76,173	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	85,886	[1]	97,028	[1]	108,743	[1]
Covered Consumer Loans [Member] [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	36		35
Financing Receivable, Modifications, Recorded Investment	5,113	[1]	5,632	[1]
Financing Receiables, Modifications, Unpaid Principal Balance	5,144	[1]	5,666	[1]
Covered TDR Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	69		68
Financing Receivable, Modifications, Recorded Investment	61,459	[1]	65,838	[1]	76,173
Financing Receiables, Modifications, Unpaid Principal Balance	$ 91,030	[1]	$ 102,694	[1]

[1] (a) The differences between the recorded investment and unpaid principal balance amounts represents partial charge offs.