Goodwill and Other Intangible Assets (Other Intangible Assets) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Net Amount	$ 662	$ 648
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	54 months	35 months
Gross Carrying Amount	$ 54	$ 12
Accumulated Amortization	9	6
Net Amount	$ 45	$ 6
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	5 years	6 years
Gross Carrying Amount	$ 2,389	$ 2,252
Accumulated Amortization	1,781	1,614
Net Amount	$ 608	$ 638
Trade names and associated trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	4 years	4 years
Gross Carrying Amount	$ 15	$ 8
Accumulated Amortization	6	4
Net Amount	$ 9	$ 4