Employee Benefit Plans - PAC - Multiemployer and Joint Trust Pension Plans (Details) - PAC - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Percentage by which joint trustee plan was at least funded	80.00%	80.00%	80.00%
Contributions	$ 6	$ 6	$ 7
UMWA Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Withdrawal liability	$ 115