Net Recognized Gains (Losses) on Debt Investments (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Sep. 30, 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	$ 19	$ 7
Realized losses from sales of available-for-sale securities	(5)	(4)
Total	125	(57)
Debt Securities
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Impairments and allowance for credit losses	3	(4)
Total	$ 17	$ (1)