Net Recognized Gains (Losses) on Equity Investments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Net realized gains on investments sold	$ 5	$ 857	$ 238	$ 2,549
Net unrealized gains on investments still held	50	0	241	0
Total	44	510	381	1,851
Equity Securities
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Other-than-temporary impairments of investments	(7)	(16)	(10)	(41)
Total	$ 48	$ 841	$ 469	$ 2,508