Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	$ 1,800	$ 0
Terminal Facilities
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	1,300	500
Terminal Facilities | Related Party
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	247	415
Related Party Transaction, Expenses from Transactions with Related Party	$ 300	$ 400