Acquisitions - Hawaii Refinery Expansion (Details) - USD ($) shares in Thousands, $ in Thousands			3 Months Ended
	Jan. 11, 2019	Dec. 19, 2018	Mar. 31, 2019
Business Acquisition [Line Items]
Issuance of common stock for business combination	$ 37,000		$ 36,980
Hawaii Refinery Expansion - Asset Acquisition
Business Acquisition [Line Items]
Consideration transferred		$ 66,900
Consideration transferred, working capital adjustments		4,300
Payments for asset acquisitions		47,600
Issuance of common stock for business combination		19,300
Property, plant and equipment, additions		45,200
Asset acquisition, non-hydrocarbon inventory		4,300
Asset acquisition, hydrocarbon inventory		$ 17,400
Common Stock
Business Acquisition [Line Items]
Common stock offering, net of issuance costs (in shares)			2,364
Issuance of common stock for business combination			$ 23
Common Stock | Hawaii Refinery Expansion - Asset Acquisition
Business Acquisition [Line Items]
Common stock offering, net of issuance costs (in shares)		1,100