Net Recognized Gains (Losses) on Equity Investments (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
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	$ 16	$ 53	$ 33	$ 75
Net unrealized gains on investments still held	326	111	426	55
Total	359	162	484	105
Equity Securities
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Impairments of investments	(2)	(9)	(11)	(31)
Total	$ 340	$ 155	$ 448	$ 99