Maturities of lease liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Jun. 30, 2018
Leases [Abstract]
Operating Leases, Year Ending June 30, 2019 (excluding the nine months ended March 31, 2019)	$ 422
Operating Leases, Year Ending June 30, 2020	1,586
Operating Leases, Year Ending June 30, 2021	1,335
Operating Leases, Year Ending June 30, 2022	1,135
Operating Leases, Year Ending June 30, 2023	942
Operating Leases, Thereafter	2,904
Operating Leases, Total lease payments	8,324
Operating Leases, Less imputed interest	(891)
Operating Leases	7,433	$ 6,967
Finance Leases, Year Ending June 30, 2019 (excluding the nine months ended March 31, 2019)	138
Finance Leases, Year Ending June 30, 2020	534
Finance Leases, Year Ending June 30, 2021	543
Finance Leases, Year Ending June 30, 2022	552
Finance Leases, Year Ending June 30, 2023	556
Finance Leases, Thereafter	5,552
Finance Leases, Total lease payments	7,875
Finance Leases, Less imputed interest	(2,065)
Finance Leases	$ 5,810	$ 4,301