Fair Value Measurements (Summary Of Gains And Losses On Level 3 Assets And Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	$ 12,709	$ 2,893	$ 36,313	$ (15,284)
Change in unrealized gains or losses relating to assets still held	14,528	5,459	39,369	(14,834)
Loan fees and sales
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	(309)	591	(1,716)	2,679
Change in unrealized gains or losses relating to assets still held	1,510	3,137	1,510	3,137
Other non-interest income
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	47	(87)	27	153
Change in unrealized gains or losses relating to assets still held	47	(87)	(143)	125
Investment Securities Gains (Losses), Net
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	12,971	2,389	38,002	(18,116)
Change in unrealized gains or losses relating to assets still held	$ 12,971	$ 2,409	$ 38,002	$ (18,096)