Net Recognized Gains (Losses) on Debt Investments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Realized gains from sales of available-for-sale securities	$ 9	$ 6	$ 30	$ 19
Realized losses from sales of available-for-sale securities	(7)	(10)	(17)	(100)
Total	(101)	44	4	381
Debt 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)	0	(12)	(7)
Total	$ (5)	$ (4)	$ 1	$ (88)