Loans and Allowances for Credit Losses Part 4 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	$ 360,258		$ 468,774
Impaired loans, recorded investment, total	294,365		386,259
Impaired loans, recorded investment with no related allowance	283,039		364,365
Impaired loans, recorded investment with related allowance	11,326		21,894
Impaired loans, related allowance	4,233		5,776
Impaired loans, average recorded investment	341,335		332,517
Impaired loans, interest income recognized	8,308		6,654
Commercial Loan [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	43,230		93,984
Impaired loans, recorded investment, total	24,467		68,811
Impaired loans, recorded investment with no related allowance	23,140		66,491
Impaired loans, recorded investment with related allowance	1,327		2,320
Impaired loans, related allowance	230		1,536
Impaired loans, average recorded investment	46,640		53,635
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Energy [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,460		336
Impaired loans, recorded investment, total	2,460		336
Impaired loans, recorded investment with no related allowance	2,460		336
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	1,398		401
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Services [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	15,715		26,916
Impaired loans, recorded investment, total	12,090		16,968
Impaired loans, recorded investment with no related allowance	11,940		16,200
Impaired loans, recorded investment with related allowance	150		768
Impaired loans, related allowance	149		360
Impaired loans, average recorded investment	14,529		18,115
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Wholesale and retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	9,186		24,432
Impaired loans, recorded investment, total	3,077		21,180
Impaired loans, recorded investment with no related allowance	3,016		19,702
Impaired loans, recorded investment with related allowance	61		1,478
Impaired loans, related allowance	15		1,102
Impaired loans, average recorded investment	12,129		14,833
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Manufacturing [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,447		26,186
Impaired loans, recorded investment, total	2,007		23,051
Impaired loans, recorded investment with no related allowance	2,007		23,051
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	12,529		12,584
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Healthcare [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	4,256		6,825
Impaired loans, recorded investment, total	3,166		5,486
Impaired loans, recorded investment with no related allowance	2,050		5,412
Impaired loans, recorded investment with related allowance	1,116		74
Impaired loans, related allowance	66		74
Impaired loans, average recorded investment	4,326		4,510
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Integrated food services [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	684		0
Impaired loans, recorded investment, total	684		0
Impaired loans, recorded investment with no related allowance	684		0
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	342		7
Impaired loans, interest income recognized	0		0
Commercial Loan [Member] | Other commercial and industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	8,482		9,289
Impaired loans, recorded investment, total	983		1,790
Impaired loans, recorded investment with no related allowance	983		1,790
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	1,387		3,185
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	86,001		141,500
Impaired loans, recorded investment, total	60,626		99,193
Impaired loans, recorded investment with no related allowance	53,051		82,080
Impaired loans, recorded investment with related allowance	7,575		17,113
Impaired loans, related allowance	3,109		3,942
Impaired loans, average recorded investment	79,911		124,782
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Construction and land development [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	44,721		98,053
Impaired loans, recorded investment, total	26,131		61,874
Impaired loans, recorded investment with no related allowance	25,575		56,740
Impaired loans, recorded investment with related allowance	556		5,134
Impaired loans, related allowance	155		1,777
Impaired loans, average recorded investment	44,003		80,727
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	9,797		8,645
Impaired loans, recorded investment, total	8,117		6,863
Impaired loans, recorded investment with no related allowance	8,117		4,373
Impaired loans, recorded investment with related allowance	0		2,490
Impaired loans, related allowance	0		1,062
Impaired loans, average recorded investment	7,490		5,921
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Office [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	8,949		14,588
Impaired loans, recorded investment, total	6,829		11,457
Impaired loans, recorded investment with no related allowance	6,604		9,567
Impaired loans, recorded investment with related allowance	225		1,890
Impaired loans, related allowance	21		291
Impaired loans, average recorded investment	9,143		15,556
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Multifamily [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	3,189		3,512
Impaired loans, recorded investment, total	2,706		3,513
Impaired loans, recorded investment with no related allowance	2,706		3,513
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	3,110		5,119
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	3,968		0
Impaired loans, recorded investment, total	3,968		0
Impaired loans, recorded investment with no related allowance	0		0
Impaired loans, recorded investment with related allowance	3,968		0
Impaired loans, related allowance	2,290		0
Impaired loans, average recorded investment	1,984		2,044
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] | Other commercial real estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	15,377		16,702
Impaired loans, recorded investment, total	12,875		15,486
Impaired loans, recorded investment with no related allowance	10,049		7,887
Impaired loans, recorded investment with related allowance	2,826		7,599
Impaired loans, related allowance	643		812
Impaired loans, average recorded investment	14,181		15,415
Impaired loans, interest income recognized	0		0
Residential Mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	228,149		229,144
Impaired loans, recorded investment, total	206,563		214,740
Impaired loans, recorded investment with no related allowance	204,264		212,279
Impaired loans, recorded investment with related allowance	2,299		2,461
Impaired loans, related allowance	769		298
Impaired loans, average recorded investment	211,672		150,059
Impaired loans, interest income recognized	8,308		6,654
Residential Mortgage [Member] | Permanent mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	51,153		35,176
Impaired loans, recorded investment, total	39,863		25,366
Impaired loans, recorded investment with no related allowance	37,564		22,905
Impaired loans, recorded investment with related allowance	2,299		2,461
Impaired loans, related allowance	769		298
Impaired loans, average recorded investment	32,614		28,739
Impaired loans, interest income recognized	1,590		527
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	170,740	[1]	189,567	[2]
Impaired loans, recorded investment, total	160,444	[1]	184,973	[2]
Impaired loans, recorded investment with no related allowance	160,444	[1]	184,973	[2]
Impaired loans, recorded investment with related allowance	0	[1]	0	[2]
Impaired loans, related allowance	0	[1]	0	[2]
Impaired loans, average recorded investment	173,729	[1]	116,462	[2]
Impaired loans, interest income recognized	6,718	[1]	6,127	[2]
Residential Mortgage [Member] | Home equity [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	6,256		4,401
Impaired loans, recorded investment, total	6,256		4,401
Impaired loans, recorded investment with no related allowance	6,256		4,401
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	5,329		4,858
Impaired loans, interest income recognized	0		0
Consumer Loan [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	2,878		4,146
Impaired loans, recorded investment, total	2,709		3,515
Impaired loans, recorded investment with no related allowance	2,584		3,515
Impaired loans, recorded investment with related allowance	125		0
Impaired loans, related allowance	125		0
Impaired loans, average recorded investment	3,112		4,041
Impaired loans, interest income recognized	0		0
Consumer Loan [Member] | Indirect automobile [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	1,578		2,194
Impaired loans, recorded investment, total	1,578		2,194
Impaired loans, recorded investment with no related allowance	1,578		2,194
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	1,886		2,360
Impaired loans, interest income recognized	0		0
Consumer Loan [Member] | Other consumer [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	1,300		1,952
Impaired loans, recorded investment, total	1,131		1,321
Impaired loans, recorded investment with no related allowance	1,006		1,321
Impaired loans, recorded investment with related allowance	125		0
Impaired loans, related allowance	125		0
Impaired loans, average recorded investment	1,226		1,681
Impaired loans, interest income recognized	$ 0		$ 0

[1] 1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2012, $489 thousand of these loans are nonaccruing and $160 million are accruing based on the guarantee by U.S. government agencies.

[2] 1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2011, all of these loans are accruing based on the guarantee by U.S. government agencies.