Segment Information - Reported Revenue and Profit Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue
Total revenue	$ (276,259)	$ (234,793)	$ (775,759)	$ (737,498)
Income (loss) before income taxes
Operating Income (Loss)	$ 21,718	6,496	55,205	39,939
Asset management fees	10.00%
Private Client Division
Revenue
Total revenue	$ (141,097)	(152,054)	(424,340)	(477,509)
Income (loss) before income taxes
Income before income taxes	25,764	35,251	83,482	121,501
Asset Management
Revenue
Total revenue	(20,632)	(18,368)	(57,423)	(53,576)
Income (loss) before income taxes
Income before income taxes	6,426	4,932	14,714	12,492
Capital markets
Revenue
Total revenue	(114,289)	(64,068)	(295,101)	(206,848)
Income (loss) before income taxes
Income before income taxes	19,369	(6,385)	41,548	(10,833)
Corporate/Other
Revenue
Total revenue	(241)	(303)	1,105	435
Income (loss) before income taxes
Income before income taxes	$ (29,841)	$ (27,302)	$ (84,539)	$ (83,221)