Pension and Other Postretirement Benefits - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Net periodic benefit cost	$ 14	$ 16	$ 27	$ 32