INCOME TAXES (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. and non-U.S. components of income (loss) before income tax expense:
U.S.		$ 172,401	$ 140,477	$ 69,734
Non-U.S.		(5,727)	3,587	(23,439)
Income (loss) before income taxes		166,674	144,064	46,295
Current income taxes:
Federal		22,178	14,483	8,242
State and Local		5,361	4,254	3,759
Foreign		(1,716)	4,314	2,492
Total		25,823	23,051	14,493
Deferred income taxes:
Federal		(848)	774	(688)
State and local		(207)	(29)	164
Foreign		41	51	(229)
Income Tax Expense (Benefit), Total		$ 24,809	$ 23,847	$ 13,740
Reconciliation of federal statutory tax rates
U.S. statutory tax rate		35.00%	35.00%	35.00%
Increase (decrease) due to state and local taxes		2.30%	2.20%	7.50%
Rate benefit as a U.S. limited partnership/flow through		(21.80%)	(22.10%)	(29.90%)
Non-deductible expenses		0.20%	0.30%	12.20%
Foreign taxes		(0.90%)	1.80%	4.90%
Other		0.10%	(0.60%)
Effective income tax rate		14.90%	16.60%	29.70%
Significant components of deferred tax assets and liabilities:
Net operating loss		$ 5,988	$ 9,043
Step-up in tax basis in Group LP assets		143,630	149,605
Deferred Compensation		21,132	10,064
Accrued expenses and other		3,995	5,965
Gross		174,745	174,677
Valuation allowance on NOL and other		(6,954)	(9,172)
Net deferred tax asset		167,791	165,505
Deferred tax assets for foreign operating loss carryforwards		5,988
Untaxed foreign earnings		0	0	$ 0
Unrecognized tax benefits		0	$ 0	$ 0
Net deferred tax asset increase		2,286
Period for cash distribution payable to partners under tax receivable agreement for tax benefits	15 years
Foreign
Significant components of deferred tax assets and liabilities:
Operating loss carryforwards		22,163
Operating loss carryforwards with indefinite life		20,129
Deferred tax assets for operating loss carryforwards for indefinite life		5,321
Operating loss carryforwards which expire on 2019 and 2023		2,034
Deferred tax assets for operating loss carryforwards which expire between 2019 and 2023		667
Group LP
Significant components of deferred tax assets and liabilities:
Deferred tax assets attributable to exchanges by partners		$ 518
Percentage of cash distribution to partners in connection to IPO attributable to exchanges by partners, payable to partners		85.00%
Cash distribution to partners in connection to IPO attributable to exchanges by partners, payable to partners		$ 440
Period of cash distribution to partners in connection to IPO attributable to exchanges by partners, payable to partners		15 years