Income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
U.S. federal:
Current	$ 27	$ 6	$ (402)
Deferred	319	328	1,158
Total U.S. federal	346	334	756
U.S. state and local:
Current	134	226	248
Deferred	1	140	457
Total U.S. state and local	$ 135	$ 366	$ 705
Reconciliation from U.S. federal statutory tax rate to effective income taxes rate
Federal statutory rate (as a percent)	34.00%	34.00%	34.00%
State and local (as a percent)	4.10%	4.60%	(5.70%)
Foreign rate differential (as a percent)	(0.50%)	(0.70%)	(3.20%)
Stock options (as a percent)	(1.50%)	(0.50%)	(0.70%)
Non-controlling interests (as a percent)	0.50%	1.90%	15.20%
Valuation allowance (as a percent)	(39.00%)	(45.10%)	(128.50%)
Transaction costs (as a percent)	0.00%	0.00%	(6.70%)
Purchase price adjustments (as a percent)	0.00%	0.00%	6.60%
Revaluation of deferred tax assets (as a percent)	0.00%	0.00%	2.80%
Uncertain tax positions (as a percent)	(0.10%)	(0.10%)	(2.90%)
Return to provision (as a percent)	0.00%	0.60%	9.30%
Other (as a percent)	0.30%	1.40%	1.10%
Effective Income Tax Rate Reconciliation, Percent, Total	(2.20%)	(3.90%)	(78.70%)
Deferred tax assets:
Net operating loss carryforwards				$ 16,895	$ 10,115
Outside basis differences for U.S. partnerships				6,190	3,710
Stock options				3,882	3,348
Deferred revenue				376	648
Deferred compensation				301	144
State taxes				67	45
Other				1,312	1,341
Valuation allowance	$ (12,470)	$ (4,101)	$ (1,669)	(19,548)	(12,470)
Net Deferred Tax Assets				9,475	6,881
Deferred tax liabilities:
Intangible assets				(6,268)	(6,855)
Property and equipment				(6,172)	(2,671)
Net deferred tax liabilities				(12,440)	(9,526)
Net deferred taxes				(2,965)	(2,645)
Net operating loss carryforwards
The tax effected amount of gross unrealized net operating loss carryforwards				6,933
Foreign loss before income taxes	$ 1,381	1,251	559
Period of cumulative results for determination of releasing valuation allowance	3 years
Changes in the valuation allowance
Balance at the beginning of the period	$ 12,470	4,101	1,669
Additions charged to operations	7,078	8,369	2,432
Decrease credited to operations	0	0	0
Balance at the end of the period	$ 19,548	$ 12,470	4,101
Windfall Tax Benefits from Stock Option Exercises			$ 55
United Kingdom
Net operating loss carryforwards
Foreign subsidiary deferred tax asset				1,528
Brazil
Net operating loss carryforwards
Foreign subsidiary deferred tax asset				476
Federal
Net operating loss carryforwards
The tax effected amount of gross unrealized net operating loss carryforwards				55,278	35,555
State
Net operating loss carryforwards
The tax effected amount of gross unrealized net operating loss carryforwards				68,614	55,457
Foreign
Net operating loss carryforwards
The tax effected amount of gross unrealized net operating loss carryforwards				$ 9,042	$ 7,661