Summary of Significant Accounting Policies - Intangibles and Impairment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impairment Long-Lived Assets
Goodwill derecognized			$ 2,932
Goodwill and long-lived asset impairment	$ 1,400	$ 600	$ 2,022	$ 414	$ 809
Minimum
Intangibles
Estimated economic useful life			3 years
Maximum
Intangibles
Estimated economic useful life			20 years
Gasoline Distribution and Station Operations Segment
Impairment Long-Lived Assets
Goodwill derecognized			$ 2,900	3,900	4,000
Impairment of goodwill			0	0
Gasoline Distribution and Station Operations Segment
Impairment Long-Lived Assets
Long-lived asset impairment			$ 2,000	$ 400	$ 800