Fair Value Measurements (Summary Of Gains And Losses On Level 3 Assets And Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gains and Losses included in earnings for Level 3 assets & liabilities [Line Items]
Total gains or losses included in earnings	$ 4,470	$ (2,314)
Change in unrealized gains or losses relating to assets still held	5,050	(1,965)
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	2	554
Change in unrealized gains or losses relating to assets still held	582	903
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	163	10
Change in unrealized gains or losses relating to assets still held	163	10
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	4,305	(2,878)
Change in unrealized gains or losses relating to assets still held	$ 4,305	$ (2,878)