Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization of $8,876 and $8,333, respectively	$ 79,519		$ 79,519		$ 80,062
Finite-Lived Intangible Assets, Gross	88,395		88,395		88,395
Amortization of Intangible Assets	271	$ 289	$ 543	$ 580
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			18 years
Finite-Lived Intangible Assets, Gross	4,918		$ 4,918		1,125
Contract-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			9 years
Finite-Lived Intangible Assets, Gross	$ 731		$ 731		$ 731
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			7 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			15 years