Segment Information - Reported Revenue and Profit Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Total revenue	$ (242,556)	$ (215,884)	$ (477,086)	$ (429,145)
Income (loss) before income taxes
Income (Loss) before income taxes from continuing operations	12,501	(1,637)	22,126	(8,662)
Private Client Division
Revenue
Total revenue	(156,553)	(140,252)	(310,647)	(277,641)
Income (loss) before income taxes
Income (Loss) before income taxes from continuing operations	$ 33,513	28,051	73,675	56,813
Asset management fees	90.00%
Asset Management
Revenue
Total revenue	$ (17,706)	(19,304)	(35,350)	(37,970)
Income (loss) before income taxes
Income (Loss) before income taxes from continuing operations	$ 3,958	4,081	7,676	7,792
Asset management fees	10.00%
Capital markets
Revenue
Total revenue	$ (68,206)	(53,707)	(129,735)	(109,610)
Income (loss) before income taxes
Income (Loss) before income taxes from continuing operations	(199)	(10,982)	(6,256)	(23,596)
Corporate/Other
Revenue
Total revenue	(91)	(2,621)	(1,354)	(3,924)
Income (loss) before income taxes
Income (Loss) before income taxes from continuing operations	$ (24,771)	$ (22,787)	$ (52,969)	$ (49,671)