Segment Reporting (Schedule Of Operating Information, Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 segment item		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of business segments									3
Number of businesses within reportable segment									2
Net revenues	$ 578,076	$ 523,455	$ 560,147	$ 546,746	$ 562,526	$ 478,639	$ 493,678	$ 438,604	$ 2,208,424	[1]	$ 1,973,446	[1]	$ 1,594,113	[1]
Income before income tax expense	69,378	65,766	77,523	78,128	77,989	31,008	52,575	23,658	290,794		185,229		229,747
Net revenues accounted for by individual client, maximum percentage									10.00%
Global Wealth Management [Member]
Segment Reporting Information [Line Items]
Net revenues									1,232,651	[1]	1,117,179	[1]	991,597	[1]
Income before income tax expense									346,978		299,572		266,669
Institutional Group [Member]
Segment Reporting Information [Line Items]
Net revenues									993,581	[1]	861,158	[1]	604,654	[1]
Income before income tax expense									152,905		142,889		101,487
Other [Member]
Segment Reporting Information [Line Items]
Net revenues									(17,808)	[1]	(4,891)	[1]	(2,138)	[1]
Income before income tax expense									$ (209,089)		$ (257,232)		$ (138,409)

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2014, 2013, or 2012.