Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Income Taxes [Line Items]
U.S. federal statutory income tax rate	35.00%
Converted expiring foreign tax credits to deductions	$ 31
Reinvested Earnings at foreign subsidiaries	211
Accrued interest and penalties	3	$ 3
Uncertain income tax position not recognized	30	$ 35
Decrease in uncertain tax position	17
Domestic Tax Authority
Schedule Of Income Taxes [Line Items]
Net operating loss carry forward	$ 548
Operating loss carry forwards, expiration year	2027
Foreign Tax Authority
Schedule Of Income Taxes [Line Items]
Foreign tax credit carry forward	$ 147
Tax credit carry forwards, expiration year	2018
United Kingdom Tax Authority
Schedule Of Income Taxes [Line Items]
Net operating loss carry forward	$ 92
France Tax Authority
Schedule Of Income Taxes [Line Items]
Net operating loss carry forward	119
Spain Tax Authority
Schedule Of Income Taxes [Line Items]
Net operating loss carry forward	$ 40