Discontinued Operations - Revenue and Expenses from Discontinued Operation (Details) - OMHHF - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
REVENUE
Interest	$ 2	$ 112	$ 7	$ 921
Principal transactions, net	0	(2,380)	0	(9,008)
Gain on sale of assets	0	0	0	14,916
Other	783	4,073	1,887	16,631
Total revenue	785	1,805	1,894	23,460
EXPENSES
Compensation and related expenses	1	573	18	4,225
Communications and technology	8	40	20	201
Occupancy and equipment costs	0	37	0	399
Interest	7	28	7	408
Other	0	239	15	2,630
Total expenses	16	917	60	7,863
Income before income taxes	769	888	1,834	15,597
Income attributable to noncontrolling interest before income taxes	$ 126	$ 145	$ 299	$ 2,545