Related Party Transactions - Omnibus Agreement (Details) - Omnibus Agreement - Martin Resource Management - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019
Related Party Transaction [Line Items]
Noncompete restriction threshold	$ 5,000,000		$ 5,000,000
Noncompete restriction ownership option opportunity threshold minimum	5,000,000		5,000,000
Noncompete restriction ownership option opportunity threshold minimum with equity limitation	$ 5,000,000		$ 5,000,000
Equity limitation on ownership restriction percentage	20.00%		20.00%
Indirect expenses reimbursed	$ 4,164,000	$ 4,104,000	$ 12,492,000	$ 12,312,000
Scenario, Forecast
Related Party Transaction [Line Items]
Approved annual reimbursements for indirect expenses					$ 16,657,000