Loans, Allowance for Loan Losses, and Credit Quality (Details 6) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	$ 2,594,029	$ 2,523,057
Installment	589,714	695,383
Total retail	3,183,743	3,218,440
Residential mortgage	2,692,054	2,346,007
Total consumer	5,875,797	5,564,447
Performing [member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	2,516,884	2,442,661
Installment	580,965	673,820
Total retail	3,097,849	3,116,481
Residential mortgage	2,579,126	2,222,916
Total consumer	5,676,975	5,339,397
30-89 Days Past Due [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	14,400	13,886
Installment	3,792	9,624
Total retail	18,192	23,510
Residential mortgage	9,385	8,722
Total consumer	27,577	32,232
Potential Problem [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	4,515	3,057
Installment	216	703
Total retail	4,731	3,760
Residential mortgage	18,575	18,672
Total consumer	23,306	22,432
Impaired [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	58,230	63,453
Installment	4,741	11,236
Total retail	62,971	74,689
Residential mortgage	84,968	95,697
Total consumer	$ 147,939	$ 170,386