Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Loans, gross of unearned income	$ 12,789,675		$ 12,154,209
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Loans, gross of unearned income	3,568,358		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	3,460,497		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	51,282	[1]	52,409	[1]
Percentage Of Total	1.40%	[1]	1.60%	[1]
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member] | Non-performing [Member]
Loans, gross of unearned income	56,579	[2]	55,878	[2]
Percentage Of Total	1.60%	[2]	1.70%	[2]
Real-estate - home equity [Member]
Loans, gross of unearned income	1,773,554		1,632,390
Real-estate - home equity [Member] | Performing [Member]
Loans, gross of unearned income	1,736,645		1,602,541
Real-estate - home equity [Member] | Delinquent [Member]
Loans, gross of unearned income	18,218	[1]	12,645	[1]
Real-estate - home equity [Member] | Non-performing [Member]
Loans, gross of unearned income	18,691	[2]	17,204	[2]
Real-estate - residential mortgage [Member]
Loans, gross of unearned income	1,327,469		1,257,432
Real-estate - residential mortgage [Member] | Performing [Member]
Loans, gross of unearned income	1,269,058		1,190,873
Real-estate - residential mortgage [Member] | Delinquent [Member]
Loans, gross of unearned income	24,102	[1]	32,123	[1]
Real-estate - residential mortgage [Member] | Non-performing [Member]
Loans, gross of unearned income	34,309	[2]	34,436	[2]
Construction other [Member]
Loans, gross of unearned income	73,444		69,216
Construction other [Member] | Performing [Member]
Loans, gross of unearned income	71,520		67,447
Construction other [Member] | Delinquent [Member]
Loans, gross of unearned income	1,425	[1]	865	[1]
Construction other [Member] | Non-performing [Member]
Loans, gross of unearned income	499	[2]	904	[2]
Total Consumer
Loans, gross of unearned income	296,142		309,864
Total Consumer | Performing [Member]
Loans, gross of unearned income	286,114		300,484
Total Consumer | Delinquent [Member]
Loans, gross of unearned income	7,015	[1]	6,065	[1]
Total Consumer | Non-performing [Member]
Loans, gross of unearned income	3,013	[2]	3,315	[2]
Consumer - direct [Member]
Loans, gross of unearned income	145,321		166,581
Consumer - direct [Member] | Performing [Member]
Loans, gross of unearned income	138,373		159,616
Consumer - direct [Member] | Delinquent [Member]
Loans, gross of unearned income	4,057	[1]	3,795	[1]
Consumer - direct [Member] | Non-performing [Member]
Loans, gross of unearned income	2,891	[2]	3,170	[2]
Consumer - Indirect [Member]
Loans, gross of unearned income	150,821		143,283
Consumer - Indirect [Member] | Performing [Member]
Loans, gross of unearned income	147,741		140,868
Consumer - Indirect [Member] | Delinquent [Member]
Loans, gross of unearned income	2,958	[1]	2,270	[1]
Consumer - Indirect [Member] | Non-performing [Member]
Loans, gross of unearned income	122	[2]	145	[2]
Leasing and other and overdrafts [Member]
Loans, gross of unearned income	97,749		86,676
Leasing and other and overdrafts [Member] | Performing [Member]
Loans, gross of unearned income	97,160		85,946
Leasing and other and overdrafts [Member] | Delinquent [Member]
Loans, gross of unearned income	522	[1]	711	[1]
Leasing and other and overdrafts [Member] | Non-performing [Member]
Loans, gross of unearned income	$ 67	[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.