Investments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Investments Schedule [Abstract]
Impairment of investment, available-for-sale securities	$ 33	$ 21

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

No definition available.

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration