Goodwill and Other Intangible Assets (Other Intangible Assets) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Net Amount	$ 576	$ 648
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	48 months	35 months
Gross Carrying Amount	$ 21	$ 12
Accumulated Amortization	7	6
Net Amount	$ 14	$ 6
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	5 years	6 years
Gross Carrying Amount	$ 2,284	$ 2,252
Accumulated Amortization	1,725	1,614
Net Amount	$ 559	$ 638
Trade names and associated trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	4 years	4 years
Gross Carrying Amount	$ 8	$ 8
Accumulated Amortization	5	4
Net Amount	$ 3	$ 4