Acquisitions - Narrative (Details) $ in Thousands		6 Months Ended
	Jan. 02, 2019 USD ($) terminal	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	[1]
Business Acquisition [Line Items]
Excess purchase price over carrying value of acquired assets		$ 102,393	$ 26
Martin Transport Inc
Business Acquisition [Line Items]
Number of terminals | terminal	23
Excess purchase price over carrying value of acquired assets	$ 102,393

[1] Financial information for 2018 has been revised to include results attributable to MTI acquired from Martin Resource Management Corporation. See Note 1 – Nature of Operations and Basis of Presentation.