Leases (Summary of Lease Costs and Supplemental Cash Flows Information) (Parenthetical) (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Dec. 31, 2019	Dec. 31, 2019
Lease Costs [Abstract]
Lease costs	[1]	$ 31	$ 61
Sublease income		$ 15	$ 25

[1] Total lease costs of $31 million and $61 million for the three and six months ended December 31, 2019, respectively, are net of sublease income of approximately $15 million and $25 million, respectively.