Loans And Allowance For Loan Losses (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Loans And Allowance For Loan Losses [Abstract]
Loans pledged at the Federal Home Loan Bank as collateral for borrowings and letters of credit obtained to secure public deposits	$ 3,700,000
Loans Pledged to the Federal Reserve Bank as collateral for discount window borrowings	1,500,000
Troubled Debt Restructured Loans	66,400
Accruing Restructured Loans	51,020		$ 38,739
Restructured Loans NonAccrual	15,400
Restructured commercial loans performing under their modified terms	33,900
Aggregate restructured credit card loans held	8,000
Restructured Loans Due to Bankruptcy Proceeding	$ 8,800
Period after which loans are deemed in default (in days)	90 days
Effect on Interest Income Resulting From Modification to Credit Card Loans	$ (927)
Commitments to lend additional funds to customers with restructured loans	12,600
Fair Value of Personal Real Estate Loans Held for Sale	4,500
Unpaid Principal Balance on Personal Real Estate Loans Held for Sale	4,300
Student Loans Held for Sale, Lower of Cost or Fair Value	5,200
Auto loans designated as held for sale	50,360	$ 0
Foreclosed real estate	2,000		2,800
Personal property acquired in repossession	$ 2,600		$ 3,300