Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Initial Carrying Value	$ 11,800	$ 11,800
Cumulative Foreign Currency Translation Adjustment	239	713
Accumulated Amortization	(1,695)	(798)
Net Carrying Value	$ 10,344	$ 11,715
Customer relationships - institutional
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	14 years	14 years
Gross Initial Carrying Value	$ 3,200	$ 3,200
Cumulative Foreign Currency Translation Adjustment	68	197
Accumulated Amortization	(332)	(156)
Net Carrying Value	$ 2,936	$ 3,241
Customer relationships - non-institutional
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	10 years	10 years
Gross Initial Carrying Value	$ 4,400	$ 4,400
Cumulative Foreign Currency Translation Adjustment	89	266
Accumulated Amortization	(645)	(304)
Net Carrying Value	$ 3,844	$ 4,362
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	10 years	10 years
Gross Initial Carrying Value	$ 1,500	$ 1,500
Cumulative Foreign Currency Translation Adjustment	30	90
Accumulated Amortization	(219)	(103)
Net Carrying Value	$ 1,311	$ 1,487
Developed technology
Finite-Lived Intangible Assets [Line Items]
Useful Life (in years)	8 years	8 years
Gross Initial Carrying Value	$ 2,700	$ 2,700
Cumulative Foreign Currency Translation Adjustment	52	160
Accumulated Amortization	(499)	(235)
Net Carrying Value	$ 2,253	$ 2,625