Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) Clients	Sep. 30, 2016 USD ($) Clients	Sep. 30, 2017 USD ($) Clients	Sep. 30, 2016 USD ($) Clients	Dec. 31, 2016 USD ($) Clients
Significant Accounting Policies [Line Items]
Clients exceeding consolidated accounts receivable percentage | Clients	0		0		0
Consolidated Accounts Receivable Percentage	10.00%		10.00%		10.00%
Clients exceeding consolidated largest client revenue | Clients	0	0	0	0
Consolidated Largest Client Revenue	10.00%	10.00%	10.00%
Option to purchase noncontrolling interest impairment charge	$ 0	$ 0	$ 0	$ 0
Beginning Balance			60,180,000
Redemptions	(337,000)	$ (520,000)	(9,650,000)
Granted			2,315,000	22,498,000
Ending Balance	60,092,000		60,092,000		$ 60,180,000
Redeemable Noncontrolling Interest [Member]
Significant Accounting Policies [Line Items]
Beginning Balance			60,180,000	$ 69,471,000	69,471,000
Redemptions			(816,000)		(1,708,000)
Granted			0		2,274,000
Changes in redemption value			299,000		(9,604,000)
Currency Translation Adjustments			429,000		(253,000)
Ending Balance	$ 60,092,000		$ 60,092,000		$ 60,180,000