Accumulated Other Comprehensive Income (Loss) - Changes in Each Component of AOCI, Net of Tax (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			$ 1,625	$ 1,625
Other comprehensive income (loss) before reclassifications	$ (110)	$ 59
Amounts reclassified from AOCI	(1)	(1)	(1)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(7)	4	3
Ending Balance	1,289			1,289
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(154)	(208)	(204)	(204)
Other comprehensive income (loss) before reclassifications	(109)	59
Amounts reclassified from AOCI	(1)	(1)	(1)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(7)	4	3
Ending Balance	(257)	(154)	(208)	(257)
Unrealized Gains on Investments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	2	2	2	2
Other comprehensive income (loss) before reclassifications	(1)
Ending Balance	1	2	2	1
Pension and Other Postretirement Benefit Liability Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(57)	(57)	(57)	(57)
Amounts reclassified from AOCI	(1)			(3)	$ 2
Ending Balance	(57)	(57)	(57)	(57)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(209)	(263)	(259)	(259)
Ending Balance	$ (313)	$ (209)	$ (263)	$ (313)