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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	$ 4,217	$ (5,305)	$ 12,642	$ (7,602)
Change in unrealized gains or losses relating to assets still held	4,947	(4,434)	13,223	(7,078)
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	(51)	(115)	98	407
Change in unrealized gains or losses relating to assets still held	679	756	679	756
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	(7)	8	173	19
Change in unrealized gains or losses relating to assets still held	(7)	8	173	19
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	4,275	(5,198)	12,371	(8,028)
Change in unrealized gains or losses relating to assets still held	$ 4,275	$ (5,198)	$ 12,371	$ (7,853)