Restructuring Charges (Summary of Restructuring Plan) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 12	$ 0
Asset impairment charges and accelerated depreciation expense
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	3
Consulting services
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	3
Contract terminations
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	2
Severance and employee-related costs
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1
Other
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 3