Non-Designated Derivative Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	$ (166)	$ 15	$ (253)	$ (49)
Foreign Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	(115)	26	(184)	(5)
Equity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	(49)	(25)	(78)	(42)
Interest Rate Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	(2)	(10)	9	(6)
Credit Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	0	2	0	4
Other Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives not designated as hedges	$ 0	$ 22	$ 0	$ 0