Income Taxes (Uncertain Tax Positions) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Change in accrual for uncertain tax positions, excluding interest and penalties
Balance, beginning of year	$ 91	$ 110	$ 102
Additions for prior year tax positions	7	1	7
Additions for current year tax positions	9	0	11
Reduction for prior year tax positions	(13)	(20)	(10)
Balance, end of year	$ 94	$ 91	$ 110