Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for doubtful accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation Allowances [Roll Forward]
Balance at beginning of year	$ 30	$ 34	$ 34
Net charges to income	14	24	17
Deductions and other	(18)	(28)	(17)
Balance at end of year	$ 26	$ 30	$ 34