Income Taxes - Differences between U.S. Federal Statutory Income Tax Rate of 35% and Income Taxes Provided (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Taxes on income at the U.S. federal statutory rate									$ 14	$ (26)	$ (115)
U.S. state and local taxes									(1)	2	1
Foreign income taxed at different rates, including withholding taxes									12	11	(15)
Increase in valuation allowance									19	34	101
Release of valuation allowance									(26)	(5)	(3)
Change in tax rates									(10)	(2)	1
Other									3	(1)	4
Total	$ (5)	$ 4	$ 15	$ (3)	$ 6	$ 4	$ (6)	$ 9	$ 11	$ 13	$ (26)