Intangible Assets (Summary Of Gross Goodwill And Accumulated Impairment Losses And Write-Offs Detailed By Reportable Segments) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015		Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 191,307,000	$ 145,932,000	$ 191,307,000	[1]	$ 145,932,000
Additions	0	0
Impairments	0	0
Divestitures	0	0
Regional Banking [Member]
Goodwill [Line Items]
Goodwill	93,303,000	47,928,000	93,303,000	[1]	47,928,000
Additions	0	0
Impairments	0	0
Divestitures	0	0
Fixed Income [Member]
Goodwill [Line Items]
Goodwill	98,004,000	98,004,000	$ 98,004,000		$ 98,004,000
Additions	0	0
Impairments	0	0
Divestitures	$ 0	$ 0

[1] The increase in goodwill was related to the TAF acquisition in fourth quarter 2015.