Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative, Notional Amount	$ 4,578,638	$ 4,525,856
Interest Rate Swaps [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,609,049	2,606,181
Interest Rate Floor [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,500,000	1,500,000
Interest Rate Caps [Member]
Derivative [Line Items]
Derivative, Notional Amount	127,358	59,316
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Derivative, Notional Amount	335,395	316,225
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	6,836	10,936
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	13,755
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	1,943
Forward TBA Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 0	$ 17,500