Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Loans, gross of unearned income	$ 12,384,755		$ 12,154,209
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Loans, gross of unearned income	3,454,251		3,355,578
Percentage Of Total	100.00%		100.00%
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member] | Performing [Member]
Loans, gross of unearned income	3,352,321		3,247,291
Percentage Of Total	97.00%		96.70%
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member] | Delinquent [Member]
Loans, gross of unearned income	44,618	[1]	52,409	[1]
Percentage Of Total	1.30%	[1]	1.60%	[1]
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member] | Non-performing [Member]
Loans, gross of unearned income	57,312	[2]	55,878	[2]
Percentage Of Total	1.70%	[2]	1.70%	[2]
Real-estate - home equity [Member]
Loans, gross of unearned income	1,689,446		1,632,390
Real-estate - home equity [Member] | Performing [Member]
Loans, gross of unearned income	1,660,350		1,602,541
Real-estate - home equity [Member] | Delinquent [Member]
Loans, gross of unearned income	11,628	[1]	12,645	[1]
Real-estate - home equity [Member] | Non-performing [Member]
Loans, gross of unearned income	17,468	[2]	17,204	[2]
Real-estate - residential mortgage [Member]
Loans, gross of unearned income	1,303,454		1,257,432
Real-estate - residential mortgage [Member] | Performing [Member]
Loans, gross of unearned income	1,240,156		1,190,873
Real-estate - residential mortgage [Member] | Delinquent [Member]
Loans, gross of unearned income	26,937	[1]	32,123	[1]
Real-estate - residential mortgage [Member] | Non-performing [Member]
Loans, gross of unearned income	36,361	[2]	34,436	[2]
Construction other [Member]
Loans, gross of unearned income	62,973		69,216
Construction other [Member] | Performing [Member]
Loans, gross of unearned income	61,908		67,447
Construction other [Member] | Delinquent [Member]
Loans, gross of unearned income	575	[1]	865	[1]
Construction other [Member] | Non-performing [Member]
Loans, gross of unearned income	490	[2]	904	[2]
Total Consumer
Loans, gross of unearned income	309,138		309,864
Total Consumer | Performing [Member]
Loans, gross of unearned income	301,722		300,484
Total Consumer | Delinquent [Member]
Loans, gross of unearned income	4,634	[1]	6,065	[1]
Total Consumer | Non-performing [Member]
Loans, gross of unearned income	2,782	[2]	3,315	[2]
Consumer - direct [Member]
Loans, gross of unearned income	168,831		166,581
Consumer - direct [Member] | Performing [Member]
Loans, gross of unearned income	163,059		159,616
Consumer - direct [Member] | Delinquent [Member]
Loans, gross of unearned income	3,148	[1]	3,795	[1]
Consumer - direct [Member] | Non-performing [Member]
Loans, gross of unearned income	2,624	[2]	3,170	[2]
Consumer - Indirect [Member]
Loans, gross of unearned income	140,307		143,283
Consumer - Indirect [Member] | Performing [Member]
Loans, gross of unearned income	138,663		140,868
Consumer - Indirect [Member] | Delinquent [Member]
Loans, gross of unearned income	1,486	[1]	2,270	[1]
Consumer - Indirect [Member] | Non-performing [Member]
Loans, gross of unearned income	158	[2]	145	[2]
Leasing and other and overdrafts [Member]
Loans, gross of unearned income	89,240		86,676
Leasing and other and overdrafts [Member] | Performing [Member]
Loans, gross of unearned income	88,185		85,946
Leasing and other and overdrafts [Member] | Delinquent [Member]
Loans, gross of unearned income	844	[1]	711	[1]
Leasing and other and overdrafts [Member] | Non-performing [Member]
Loans, gross of unearned income	$ 211	[2]	$ 19	[2]

[1] )Includes all accruing loans 31 days to 89 days past due

[2] )Includes all accruing loans 90 days or more past due and all non-accrual loans.