Commitments And Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments And Contingencies [Line Items]
Letters of credit outstanding, amount	$ 176,100,000	$ 175,700,000
Mortgage loans sold	3,971,724,000	3,241,489,000	$ 3,862,030,000
Additional amount related to loss indemnification claims for residential mortgage loans previously sold to investors	4,000,000	3,100,000
Losses charged against indemnification liability	1,100,000	435,000
Customer balances maintained by clearing broker and subject to indemnification	26,700,000
Commitments to extend credit
Commitments And Contingencies [Line Items]
Derivative, notional amount	473,400,000	427,400,000
Forward commitments to sell mortgage loans
Commitments And Contingencies [Line Items]
Derivative, notional amount	753,900,000	753,900,000	$ 575,400,000
Commercial, Commercial Real Estate And Construction Loans [Member]
Commitments And Contingencies [Line Items]
Loans and leases receivable, commitments	3,700,000,000	3,100,000,000
Home equity
Commitments And Contingencies [Line Items]
Loans and leases receivable, commitments	$ 855,100,000	$ 744,300,000