Loans and Allowances for Credit Losses Part 4 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	$ 341,939	$ 436,365	$ 360,258
Impaired loans, recorded investment, total	294,838	364,221	294,365
Impaired loans, recorded investment with no related allowance	291,772	355,452	283,039
Impaired loans, recorded investment with related allowance	3,066	8,769	11,326
Impaired loans, related allowance	1,027	2,337	4,233
Impaired loans, average recorded investment	294,606	386,710
Impaired loans, interest income recognized	1,594	1,664
Commercial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	31,764	87,091	43,230
Impaired loans, recorded investment, total	19,861	61,750	24,467
Impaired loans, recorded investment with no related allowance	18,794	59,734	23,140
Impaired loans, recorded investment with related allowance	1,067	2,016	1,327
Impaired loans, related allowance	348	464	230
Impaired loans, average recorded investment	22,165	65,281
Impaired loans, interest income recognized	0	0
Commercial [Member] | Energy [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,377	336	2,460
Impaired loans, recorded investment, total	2,377	336	2,460
Impaired loans, recorded investment with no related allowance	2,377	336	2,460
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	2,419	336
Impaired loans, interest income recognized	0	0
Commercial [Member] | Services [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	12,592	22,318	15,715
Impaired loans, recorded investment, total	9,474	12,890	12,090
Impaired loans, recorded investment with no related allowance	8,502	12,237	11,940
Impaired loans, recorded investment with related allowance	972	653	150
Impaired loans, related allowance	292	307	149
Impaired loans, average recorded investment	10,782	14,929
Impaired loans, interest income recognized	0	0
Commercial [Member] | Wholesale/retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,545	19,085	9,186
Impaired loans, recorded investment, total	2,239	15,388	3,077
Impaired loans, recorded investment with no related allowance	2,187	15,300	3,016
Impaired loans, recorded investment with related allowance	52	88	61
Impaired loans, related allowance	13	22	15
Impaired loans, average recorded investment	2,658	18,284
Impaired loans, interest income recognized	0	0
Commercial [Member] | Manufacturing [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,140	26,536	2,447
Impaired loans, recorded investment, total	1,848	23,402	2,007
Impaired loans, recorded investment with no related allowance	1,848	23,402	2,007
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	1,928	23,227
Impaired loans, interest income recognized	0	0
Commercial [Member] | Healthcare [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	3,649	9,529	4,256
Impaired loans, recorded investment, total	2,962	7,946	3,166
Impaired loans, recorded investment with no related allowance	2,919	6,671	2,050
Impaired loans, recorded investment with related allowance	43	1,275	1,116
Impaired loans, related allowance	43	135	66
Impaired loans, average recorded investment	3,064	6,716
Impaired loans, interest income recognized	0	0
Commercial [Member] | Integrated food services [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	0	0	684
Impaired loans, recorded investment, total	0	0	684
Impaired loans, recorded investment with no related allowance	0	0	684
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	342	0
Impaired loans, interest income recognized	0	0
Commercial [Member] | Other commercial and industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	8,461	9,287	8,482
Impaired loans, recorded investment, total	961	1,788	983
Impaired loans, recorded investment with no related allowance	961	1,788	983
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	972	1,789
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	80,379	127,690	86,001
Impaired loans, recorded investment, total	65,175	86,475	60,626
Impaired loans, recorded investment with no related allowance	63,846	80,402	53,051
Impaired loans, recorded investment with related allowance	1,329	6,073	7,575
Impaired loans, related allowance	258	1,644	3,109
Impaired loans, average recorded investment	62,902	92,835
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Construction and land development [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	28,913	86,435	44,721
Impaired loans, recorded investment, total	23,462	52,416	26,131
Impaired loans, recorded investment with no related allowance	22,967	51,615	25,575
Impaired loans, recorded investment with related allowance	495	801	556
Impaired loans, related allowance	155	206	155
Impaired loans, average recorded investment	24,797	57,145
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	11,375	7,680	9,797
Impaired loans, recorded investment, total	8,921	6,193	8,117
Impaired loans, recorded investment with no related allowance	8,921	3,761	8,117
Impaired loans, recorded investment with related allowance	0	2,432	0
Impaired loans, related allowance	0	1,062	0
Impaired loans, average recorded investment	8,519	6,528
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Office [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	16,169	13,888	8,949
Impaired loans, recorded investment, total	12,851	10,733	6,829
Impaired loans, recorded investment with no related allowance	12,617	10,508	6,604
Impaired loans, recorded investment with related allowance	234	225	225
Impaired loans, related allowance	30	21	21
Impaired loans, average recorded investment	9,840	11,095
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Multifamily [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	4,501	3,414	3,189
Impaired loans, recorded investment, total	4,501	3,414	2,706
Impaired loans, recorded investment with no related allowance	4,501	3,414	2,706
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	3,604	3,464
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	3,875	0	3,968
Impaired loans, recorded investment, total	2,198	0	3,968
Impaired loans, recorded investment with no related allowance	2,198	0	0
Impaired loans, recorded investment with related allowance	0	0	3,968
Impaired loans, related allowance	0	0	2,290
Impaired loans, average recorded investment	3,083	0
Impaired loans, interest income recognized	0	0
Commercial Real Estate [Member] | Other commercial real estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	15,546	16,273	15,377
Impaired loans, recorded investment, total	13,242	13,719	12,875
Impaired loans, recorded investment with no related allowance	12,642	11,104	10,049
Impaired loans, recorded investment with related allowance	600	2,615	2,826
Impaired loans, related allowance	73	355	643
Impaired loans, average recorded investment	13,059	14,603
Impaired loans, interest income recognized	0	0
Residential Mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	227,559	213,281	228,149
Impaired loans, recorded investment, total	207,631	208,324	206,563
Impaired loans, recorded investment with no related allowance	207,083	207,644	204,264
Impaired loans, recorded investment with related allowance	548	680	2,299
Impaired loans, related allowance	299	229	769
Impaired loans, average recorded investment	207,098	223,000
Impaired loans, interest income recognized	1,594	1,664
Residential Mortgage [Member] | Permanent mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	48,613	24,131	51,153
Impaired loans, recorded investment, total	38,153	22,822	39,863
Impaired loans, recorded investment with no related allowance	37,605	22,142	37,564
Impaired loans, recorded investment with related allowance	548	680	2,299
Impaired loans, related allowance	299	229	769
Impaired loans, average recorded investment	39,008	24,094
Impaired loans, interest income recognized	318	132
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	171,887	184,510	170,740
Impaired loans, recorded investment, total	162,419	180,862	160,444
Impaired loans, recorded investment with no related allowance	162,419	180,862	160,444
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	161,432	194,385
Impaired loans, interest income recognized	1,276	1,532
Residential Mortgage [Member] | Home equity [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	7,059	4,640	6,256
Impaired loans, recorded investment, total	7,059	4,640	6,256
Impaired loans, recorded investment with no related allowance	7,059	4,640	6,256
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	6,658	4,521
Impaired loans, interest income recognized	0	0
Consumer [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,237	8,303	2,878
Impaired loans, recorded investment, total	2,171	7,672	2,709
Impaired loans, recorded investment with no related allowance	2,049	7,672	2,584
Impaired loans, recorded investment with related allowance	122	0	125
Impaired loans, related allowance	122	0	125
Impaired loans, average recorded investment	2,441	5,594
Impaired loans, interest income recognized	0	0
Consumer [Member] | Indirect automobile [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	1,319	2,608	1,578
Impaired loans, recorded investment, total	1,319	2,608	1,578
Impaired loans, recorded investment with no related allowance	1,319	2,608	1,578
Impaired loans, recorded investment with related allowance	0	0	0
Impaired loans, related allowance	0	0	0
Impaired loans, average recorded investment	1,449	2,401
Impaired loans, interest income recognized	0	0
Consumer [Member] | Other consumer [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	918	5,695	1,300
Impaired loans, recorded investment, total	852	5,064	1,131
Impaired loans, recorded investment with no related allowance	730	5,064	1,006
Impaired loans, recorded investment with related allowance	122	0	125
Impaired loans, related allowance	122	0	125
Impaired loans, average recorded investment	992	3,193
Impaired loans, interest income recognized	$ 0	$ 0