Business Combinations - Allocation of Total Consideration to Fair Value of Assets and Liabilities of Quality Carriers (Details) - USD ($) $ in Millions	Dec. 31, 2021	Jul. 01, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets Acquired:
Goodwill	$ 276		$ 63	$ 63
Quality Carriers
Assets Acquired:
Cash and Cash Equivalents		$ 3
Accounts Receivable, net		113
Properties and Equipment, net		225
Goodwill		213
Intangible Assets		180
Other Assets		9
Total Assets Acquired		743
Liabilities Assumed:
Accounts Payable and Accrued Liabilities		48
Finance Lease Obligations and Notes Payable		68
Casualty, Environmental and Other Reserves		62
Other Long-term Liabilities		21
Total Liabilities Assumed		199
Fair Value of Assets Acquired, Net of Liabilities Assumed:		$ 544