Commitments and Contingencies Commitments and Contingencies (European Commission Investigation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Loss Contingency, Loss in Period	$ 2	$ 0	$ 2	$ 0
European Commission Competition Law Investigation
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss						$ 89
European Commission Competition Law Investigation | Settled Litigation
Loss Contingencies [Line Items]
Loss Contingency, Loss in Period					$ 92