Acquisitions, Disposals and Other Transactions - Schedule of Total Fair Value of iProperty at Acquisition Date (Detail) $ in Millions, $ in Millions		1 Months Ended		12 Months Ended
		Feb. 29, 2016 USD ($)	Feb. 29, 2016 AUD ($)	Jun. 30, 2018 USD ($)
Business Acquisition [Line Items]
Total consideration	[1]			$ 914
REA Group [Member] | iProperty Group Limited [Member]
Business Acquisition [Line Items]
Cash paid for iProperty equity		$ 340	$ 482
Deferred consideration		76
Total consideration		416
Fair value of previously held iProperty investment		120
Total fair value		$ 536

[1] See Note 3-Acquisitions, Disposals and Other Transactions.