Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Requisite service period	30 days
Employer matching contribution, percent of match	6.00%
Employers matching contribution, vesting percentage	100.00%
Defined contribution plan, maximum annual contributions per employee, amount	$ 130,000
Total plan contributions	$ 5,600,000	$ 5,600,000	$ 4,000,000.0
Period with five consecutive years of highest average compensation	10 years
Wyoming Refining plan
Defined Benefit Plan Disclosure [Line Items]
Expected future employer contributions, next fiscal year	$ 200,000
U.S. Oil plan
Defined Benefit Plan Disclosure [Line Items]
Expected future employer contributions, next fiscal year	$ 0