Equity-Based Compensation (Summary of Equity-Based Compensation) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity-based compensation	[1]	$ 42	$ 12	$ 74	$ 33
Intrinsic value of all settled equity-based awards		$ 3	$ 8	$ 6	$ 110

[1] Prior to the Distribution, equity-based compensation included allocated expense for both executive directors and corporate executives of 21CF, allocated using a proportional allocation driver, which management deemed to be reasonable.