Maturities of lease liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Leases [Abstract]
Operating Leases, Year Ending June 30, 2019 (excluding six months ended December 31, 2018)	$ 799
Operating Leases, Year Ending June 30, 2020	1,503
Operating Leases, Year Ending June 30, 2021	1,244
Operating Leases, Year Ending June 30, 2022	1,048
Operating Leases, Year Ending June 30, 2023	861
Operating Leases, Thereafter	2,439
Operating Leases, Total lease payments	7,894
Operating Leases, Less imputed interest	(790)
Operating Leases	7,104	$ 6,967
Finance Leases, Year Ending June 30, 2019 (excluding the six months ended December 31, 2018)	241
Finance Leases, Year Ending June 30, 2020	479
Finance Leases, Year Ending June 30, 2021	487
Finance Leases, Year Ending June 30, 2022	495
Finance Leases, Year Ending June 30, 2023	498
Finance Leases, Thereafter	4,934
Finance Leases, Total lease payments	7,134
Finance Leases, Less imputed interest	(1,924)
Finance Leases	$ 5,210	$ 4,301