Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 20, 2017
Income Taxes
Interest held by parent	61.50%			61.50%
Interest held by non-controlling owners	38.50%			38.50%
Effective tax rate	33.70%
Anticipated Tax Distributions	$ 597
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
Deferred tax assets	$ 6,220	$ 476