Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional Amount of Derivatives	$ 1,933,725	$ 1,904,093
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,723,448	1,685,099
Interest Rate Caps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	31,923	59,379
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Notional Amount of Derivatives	112,348	121,514
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	8,783	4,046
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Notional Amount of Derivatives	23,616	12,429
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,607	6,626
Forward TBA Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	$ 32,000	$ 15,000