Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 47,810,000	$ 51,350,000	$ 43,979,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	16,094,000	15,124,000	15,316,000
Bad debt expense	1,195,000	433,000	630,000
Loss (gain) on sale or disposition of assets, net	178,000	(3,397,000)	(14,000)
Loss on early extinguishment of debt	796,000	94,000	178,000
Equity in earnings of investees		(1,215,000)	(600,000)
Distributions received from equity investees		1,178,000	549,000
Equity-based compensation expense	2,330,000	1,453,000	2,002,000
Non-cash interest expense	445,000	439,000	365,000
Deferred income tax expense	3,473,000	2,531,000	1,865,000
Changes in operating assets and liabilities:
Accounts and notes receivable, current portion	(3,841,000)	(999,000)	(1,466,000)
Advances from/to affiliates	71,000	(771,000)	(161,000)
Other current and noncurrent assets	362,000	502,000	100,000
Other current and noncurrent liabilities	(2,865,000)	7,000,000	1,816,000
Income taxes receivable/payable	(71,000)	2,770,000	(222,000)
Deferred revenue and deposits current portion	(254,000)	866,000	1,094,000
Payment pursuant to tax receivable agreement	(1,344,000)	0	(986,000)
Net cash provided by operating activities	64,379,000	77,358,000	64,445,000
Cash flows from investing activities:
Purchases of property, equipment and software	(4,395,000)	(3,546,000)	(2,026,000)
Proceeds from sale of property and equipment	50,000	25,000	5,000
Capitalization of trademark costs	(107,000)	(82,000)	(122,000)
Acquisitions, net of cash acquired of $466	(112,934,000)
Dispositions	200,000	5,650,000	100,000
Cost to sell assets	(146,000)	(383,000)
Net cash provided by (used in) investing activities	(117,332,000)	1,664,000	(2,043,000)
Cash flows from financing activities:
Proceeds from issuance of debt, net	233,825,000
Payments on debt	(203,223,000)	(9,400,000)	(16,816,000)
Debt issuance and capitalized debt amendment costs	(1,379,000)	(555,000)
Distributions to non-controlling unitholders	(17,927,000)	(42,827,000)	(22,197,000)
Dividends paid to Class A common stockholders	(10,578,000)	(24,003,000)	(2,901,000)
Payments on capital lease obligations	(75,000)	(322,000)	(204,000)
Proceeds from exercise of stock options	101,000	2,248,000	486,000
Payment of payroll taxes related to net settled restricted stock units	(516,000)	(327,000)	(1,781,000)
Net cash provided by (used in) financing activities	228,000	(75,186,000)	(43,413,000)
Effect of exchange rate changes on cash	122,000	(823,000)	(165,000)
Net (decrease) increase in cash and cash equivalents	(52,603,000)	3,013,000	18,824,000
Cash and cash equivalents, beginning of year	110,212,000	107,199,000	88,375,000
Cash and cash equivalents, end of year	57,609,000	110,212,000	107,199,000
Supplemental disclosures of cash flow information:
Cash paid for interest and debt amendment costs	7,797,000	9,319,000	8,880,000
Net cash paid for income taxes	11,912,000	5,841,000	8,521,000
Schedule of non-cash investing and financing activities:
Establishment of amounts payable under tax receivable agreements		33,018,000	436,000
Establishment of deferred tax assets		43,774,000	917,000
Note receivable received as consideration for sale of brokerage operations assets	150,000	851,000
Capital leases for property and equipment	48,000	412,000	18,000
Increase in accounts payable for capitalization of trademark costs and purchases of property, equipment and software	150,000	$ 667,000	$ 165,000
Contingent consideration issued in a business combination	$ 6,400,000