Fair Value Measurements (Summary Of Gains And Losses On Level 3 Assets And Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	$ (13,494)	$ (1,527)
Change in unrealized gains or losses relating to assets still held	(13,063)	(991)
Loans Fees And Sales [Member]
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	(459)	287
Change in unrealized gains or losses relating to assets still held	0	823
Other Non-Interest Income [Member]
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	(27)	28
Change in unrealized gains or losses relating to assets still held	(55)	28
Investment Securities Gains (Losses), Net [Member]
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	(13,008)	(1,842)
Change in unrealized gains or losses relating to assets still held	$ (13,008)	$ (1,842)