Acquisitions, Disposals and Other Transactions - Schedule of Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Feb. 29, 2016	Jun. 30, 2015	Nov. 30, 2014
Assets Acquired:
Goodwill	$ 3,838		$ 3,714		$ 3,063
Wireless Group plc [Member]
Assets Acquired:
Intangible assets		$ 220
Goodwill		115
Liabilities assumed:
Borrowings		23
Net liabilities		(50)
Total net assets acquired		$ 285
iProperty Group Limited [Member] | REA Group [Member]
Assets Acquired:
Intangible assets				$ 72
Goodwill				498
Liabilities assumed:
Net liabilities				(34)
Total net assets acquired				$ 536
Move Inc [Member]
Assets Acquired:
Cash						$ 108
Other current assets						28
Intangible assets						216
Deferred income taxes						153
Goodwill						552
Other non-current assets						69
Total assets acquired						1,126
Liabilities assumed:
Current liabilities						50
Deferred income taxes						52
Borrowings						129
Other non-current liabilities						3
Total liabilities assumed						234
Total net assets acquired						$ 892