Related Party Transactions - Omnibus Agreement (Details) - Omnibus Agreement - Martin Resource Management - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction
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%
Approved annual reimbursements for indirect expenses					$ 16,410,000
Indirect expenses reimbursed	$ 4,103,000	$ 4,164,000	$ 8,261,000	$ 8,328,000