Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative, Notional Amount	$ 4,178,156	$ 3,254,921
Interest Rate Swaps [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,353,450	2,006,280
Interest Rate Floor [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,500,000	1,000,000
Interest Rate Caps [Member]
Derivative [Line Items]
Derivative, Notional Amount	59,782	62,163
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Derivative, Notional Amount	195,930	143,460
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	5,481	6,206
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Derivative, Notional Amount	24,889	14,544
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	4,124	5,768
Forward TBA Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 34,500	$ 16,500