Loans, Allowance for Loan Losses, and Credit Quality Consumer Loans by Credit Quaility Indicator (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	$ 1,636,058	$ 1,825,014
Installment and Credit Cards	454,219	407,074
Residential mortgage	4,472,760	3,835,591
Total consumer	6,563,037	6,067,679
Performing Financing Receivable [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	1,592,788	1,777,421
Installment and Credit Cards	450,698	404,514
Residential mortgage	4,397,271	3,758,688
Total consumer	6,440,757	5,940,623
Thirty To Eighty Nine Days Past Due [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	10,583	10,680
Installment and Credit Cards	1,932	1,150
Residential mortgage	3,046	6,118
Total consumer	15,561	17,948
Potential Problem [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	880	2,113
Installment and Credit Cards	2	50
Residential mortgage	3,781	3,312
Total consumer	4,663	5,475
Impaired [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	31,807	34,800
Installment and Credit Cards	1,587	1,360
Residential mortgage	68,662	67,473
Total consumer	$ 102,056	$ 103,633