Segment Reporting (Schedule Of Operating Information, Segment) (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | item										3
Net revenues	[1]									$ 2,331,594	$ 2,208,424	$ 1,973,446
Income before income tax expense		$ 11,082	$ 22,348	$ 38,071	$ 70,066	$ 69,378	$ 65,766	$ 77,523	$ 78,128	$ 141,567	$ 290,794	$ 185,229
Net revenues accounted for by individual client, maximum percentage										10.00%	10.00%	10.00%
Global Wealth Management [Member]
Segment Reporting Information [Line Items]
Number of operating segments | item										2
Net revenues	[1]									$ 1,377,313	$ 1,232,651	$ 1,117,179
Income before income tax expense										382,126	346,978	299,572
Institutional Group [Member]
Segment Reporting Information [Line Items]
Net revenues	[1]									975,594	997,071	864,371
Income before income tax expense										141,042	165,546	149,599
Other [Member]
Segment Reporting Information [Line Items]
Net revenues	[1]									(21,313)	(21,298)	(8,104)
Income before income tax expense										$ (381,601)	$ (221,730)	$ (263,942)

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2015, 2014, and 2013.