Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount of Derivatives	$ 3,277,127	$ 3,254,921
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,007,799	2,006,280
Interest Rate Floor [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,000,000	1,000,000
Interest Rate Caps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	61,696	62,163
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Notional Amount of Derivatives	142,266	143,460
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	6,710	6,206
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Notional Amount of Derivatives	22,496	14,544
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,657	5,768
Forward TBA Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	$ 33,503	$ 16,500