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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Change in unrealized gains or losses relating to assets still held at period end	$ 5,605	$ 14,050	$ 17,446	$ 37,083
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	5,605	14,050	16,946	37,133
Change in unrealized gains or losses relating to assets still held at period end	$ 5,605	$ 14,050	$ 17,446	$ 37,083