Intangible Assets (Summary Of Gross Goodwill And Accumulated Impairment Losses And Write-Offs Detailed By Reportable Segments) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Goodwill [Line Items]
Goodwill, Beginning balance	$ 191,371	$ 191,307
Additions	44,964	64
Goodwill, Ending balance	236,335	191,371
Regional Banking
Goodwill [Line Items]
Goodwill, Beginning balance	93,367	93,303
Additions	0	64
Goodwill, Ending balance	93,367	93,367
Fixed Income
Goodwill [Line Items]
Goodwill, Beginning balance	98,004	98,004
Additions	44,964	0
Goodwill, Ending balance	$ 142,968	$ 98,004