Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation between the statutory federal income tax rate and the effective income tax rate
Federal statutory income tax rate (as a percent)	21.00%	35.00%	35.00%
State income tax rate, net of federal tax benefit (as a percent)	2.80%	1.20%	(0.70%)
Impairment of goodwill	0.30%	1.60%	(2.20%)
Federal deferred rate change		(65.50%)
Partnership income not subject to tax (as a percent)	(18.90%)	(42.50%)	(32.10%)
Effective income tax rate (as a percent)	5.20%	(70.20%)
Current:
Federal	$ 162	$ 1,371	$ 14,499
State	2,706	1,011	4,345
Foreign	4	4	(9)
Total current	2,872	2,386	18,835
Deferred:
Federal	1,961	(25,217)	(13,480)
State	790	(732)	(5,302)
Total deferred	2,751	(25,949)	(18,782)
Income Tax Expense (Benefit), Total	$ 5,623	$ (23,563)	$ 53