Net Recognized Gains (Losses) on Equity Investments (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
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	$ 203	$ 646
Net unrealized gains on investments still held	118	0
Total	243	573
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	0	(5)
Total	$ 321	$ 641