Loans, Allowance for Loan Losses, and Credit Quality (Details 5) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	$ 2,571,404	$ 2,523,057
Installment	572,243	695,383
Total retail	3,143,647	3,218,440
Residential mortgage	2,840,458	2,346,007
Total consumer	5,984,105	5,564,447
Performing [member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	2,491,589	2,442,661
Installment	565,855	673,820
Total retail	3,057,444	3,116,481
Residential mortgage	2,728,889	2,222,916
Total consumer	5,786,333	5,339,397
30-89 Days Past Due [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	18,165	13,886
Installment	1,956	9,624
Total retail	20,121	23,510
Residential mortgage	12,114	8,722
Total consumer	32,235	32,232
Potential Problem [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	4,975	3,057
Installment	272	703
Total retail	5,247	3,760
Residential mortgage	16,550	18,672
Total consumer	21,797	22,432
Impaired [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	56,675	63,453
Installment	4,160	11,236
Total retail	60,835	74,689
Residential mortgage	82,905	95,697
Total consumer	$ 143,740	$ 170,386