Related Party Transactions and 21CF Investment (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
General Corporate Expenses	$ 95	$ 83	$ 180	$ 137