Loans, Allowance for Loan Losses, and Credit Quality Consumer Loans by Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	$ 1,891,378	$ 2,219,494
Installment	420,268	466,727
Residential mortgage	3,690,177	3,376,697
Total consumer	6,001,823	6,062,918
Performing Financing Receivable [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	1,843,939	2,153,103
Installment	417,346	462,016
Residential mortgage	3,609,947	3,276,889
Total consumer	5,871,232	5,892,008
Thirty To Eighty Nine Days Past Due [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	9,900	13,538
Installment	1,170	2,109
Residential mortgage	6,722	9,403
Total consumer	17,792	25,050
Potential Problem [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	2,237	3,670
Installment	67	111
Residential mortgage	5,342	8,762
Total consumer	7,646	12,543
Impaired [Member]
Consumer Loans By Credit Quality Indicator [Abstract]
Home equity	35,302	49,183
Installment	1,685	2,491
Residential mortgage	68,166	81,643
Total consumer	$ 105,153	$ 133,317