Acquisitions - Hawaii Refinery Expansion (Details) - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
	Dec. 19, 2018	Dec. 31, 2018	Dec. 31, 2016
Schedule of Asset Acquisition [Line Items]
Asset acquisition, consideration transferred	$ 66,900
Issuance of common stock in connection with acquisition		$ 19,318	$ 49,044
Common Stock
Schedule of Asset Acquisition [Line Items]
Issuance of common stock in connection with acquisition (in shares)		1,108	4,075
Issuance of common stock in connection with acquisition		$ 11	$ 41
Hawaii Refinery Expansion - Asset Acquisition
Schedule of Asset Acquisition [Line Items]
Asset acquisition, consideration transferred, working capital adjustments	4,300
Payments for asset acquisitions	47,600
Issuance of common stock in connection with acquisition	19,300
Property, plant and equipment, additions	45,200
Asset acquisition, non-hydrocarbon inventory	4,300
Asset acquisition, hydrocarbon inventory	$ 17,400
Asset acquisition, transaction costs		$ 5,700
Hawaii Refinery Expansion - Asset Acquisition | Common Stock
Schedule of Asset Acquisition [Line Items]
Issuance of common stock in connection with acquisition (in shares)	1,100