Segment Information - Reported Revenue and Profit Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue
Total revenue	$ (237,814)	$ (226,220)	$ (714,900)	$ (655,365)
Income (loss) before income taxes
Income before income taxes from continuing operations	7,144	11,828	29,270	3,166
Private Client Division
Revenue
Total revenue	(158,083)	(147,428)	(468,730)	(425,069)
Income (loss) before income taxes
Income before income taxes from continuing operations	$ 37,608	36,950	111,283	93,763
Asset management fees	90.00%
Asset Management
Revenue
Total revenue	$ (17,870)	(19,277)	(53,220)	(57,247)
Income (loss) before income taxes
Income before income taxes from continuing operations	$ 4,127	3,338	11,803	11,130
Asset management fees	10.00%
Capital markets
Revenue
Total revenue	$ (68,130)	(58,808)	(197,865)	(168,418)
Income (loss) before income taxes
Income before income taxes from continuing operations	(2,076)	(1,639)	(8,332)	(25,235)
Corporate/Other
Revenue
Total revenue	6,269	(707)	4,915	(4,631)
Income (loss) before income taxes
Income before income taxes from continuing operations	$ (32,515)	$ (26,821)	$ (85,484)	$ (76,492)