Gains (Losses) on Fair Value Hedges and Related Hedged Items (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Foreign Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives	$ 14	$ 685	$ 36	$ 637
Hedged items	12	(674)	10	(606)
Total amount of ineffectiveness	26	11	46	31
Equity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives	(71)	(7)	(307)	(17)
Hedged items	71	7	307	17
Total amount of ineffectiveness	0	0	0	0
Amount of equity contracts excluded from effectiveness assessment	$ 20	$ (1)	$ 60	$ (4)