Commitments and Contingencies - Contingencies (Details) - Martin Resource Management $ in Thousands		12 Months Ended
	Oct. 02, 2012 USD ($) quarter	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Quarterly purchase price reimbursement for non compliance	$ 750	$ 1,125	$ 4,125
Quarterly purchase price reimbursement for non compliance, number of consecutive quarters | quarter	4
Maximum purchase price reimbursement for non compliance			$ 4,500