Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount of Derivatives	$ 2,672,156	$ 1,963,178
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,922,172	1,741,412
Interest Rate Floor [Member]
Derivative [Line Items]
Notional Amount of Derivatives	500,000	0
Interest Rate Caps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	30,416	31,776
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Notional Amount of Derivatives	158,764	133,488
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	6,087	11,826
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Notional Amount of Derivatives	24,997	17,110
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,720	2,566
Forward TBA Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	$ 27,000	$ 25,000