Income Taxes (Schedule Of Tax Effects Of Deferred Tax Assets And Deferred Tax Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Gross deferred tax assets, Book loan loss deduction in excess of tax	$ 240,881	$ 254,223
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits	19,332	24,749
Gross deferred tax assets, Deferred compensation	87,420	91,665
Gross deferred tax assets, Security investments and derivative fair value adjustments	56,628	11,254
Gross deferred tax assets, Net operating losses, capital losses and tax credits	4,664	4,659
FDIC Supported Transactions	5,086	9,157
Gross deferred tax assets, Other	46,052	46,016
Gross deferred tax assets	460,063	441,723
Gross deferred tax assets, Valuation allowance	(4,100)	(4,300)
Total deferred tax assets	455,936	437,462
Gross deferred tax liabilities, Core deposits and purchase accounting	(1,140)	(3,392)
Gross deferred tax liabilities, Premises and equipment, due to differences in depreciation	(7,548)	(10,588)
Gross deferred tax liabilities, FHLB stock dividends	(3,800)	(10,042)
Gross deferred tax liabilities, Leasing operations	(75,109)	(85,255)
Gross deferred tax liabilities, Prepaid expenses	(6,534)	(9,001)
Gross deferred tax liabilities, Prepaid pension reserves	(17,659)	(18,087)
Deferred Tax Liabilities, Mortgage Servicing Rights	(9,844)	(6,845)
Gross deferred tax liabilities, Subordinated debt modification	(30,762)	(46,451)
Deferred Tax Liabilities, Financing Arrangements	25,425	23,723
Deferred Tax Liabilities, Investments	27,651	21,037
Total deferred tax liabilities	(205,472)	(234,421)
Net deferred tax assets	$ 250,464	$ 203,041