Other Assets - Components of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 2,583	$ 4,295
Investments in merchant banking funds	1,209	1,689
Rent deposits	1,798	1,517
Other tangible assets	639	540
Intangible assets	50	300
Total other assets	$ 6,279	$ 8,341