Pension and Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Net periodic benefit cost	$ 13	$ 14	$ 27	$ 27