Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income taxes
Effective tax rate on income from continuing operations (as a percent)	23.50%	15.40%	17.40%	15.80%
Valuation allowance	$ 12		$ 12		$ 19
Gross unrecognized tax benefits	111		111		100
Unrecognized tax benefits net of federal tax benefits that would affect the effective tax rate	82		82		67
Increase in interest and penalties	1		2	$ 1
Decrease in interest and penalties		$ 1
Payable related to accrued interest and penalties	10		10		$ 8
Minimum [Member]
Income taxes
Amount of decrease in unrecognized tax benefits reasonably possible within next 12 months	0		0
Maximum [Member]
Income taxes
Amount of decrease in unrecognized tax benefits reasonably possible within next 12 months	10		10
State and Local [Member]
Income taxes
Deferred tax assets, loss carryforwards	18		18
Valuation allowance, net operating losses	10		10
Valuation allowance	$ 2		$ 2