Derivative Instruments and Hedging Activities - Additional Information (Detail) shares in Millions, ¥ in Billions	3 Months Ended			9 Months Ended
	Jun. 30, 2016 USD ($) shares Swap	Jun. 30, 2015 USD ($) shares Swap	Sep. 30, 2005 USD ($) Agreement	Jun. 30, 2016 USD ($) shares Swap	Jun. 30, 2015 USD ($) shares Swap	Jun. 30, 2016 JPY (¥) shares Swap	Sep. 30, 2015 USD ($) shares Swap	Sep. 30, 2015 JPY (¥) shares Swap	Jun. 30, 2015 JPY (¥) shares Swap	Mar. 31, 2006 Agreement
Derivative [Line Items]
Hedge percentage for foreign exchange transactional exposures, Minimum				70.00%
Hedge percentage for foreign exchange transactional exposures, Maximum				90.00%
Number of fixed to floating interest rate swaps outstanding | Swap	8	12		8	12	8	12	12	12
Number of forward treasury lock agreements | Agreement			3
Types Of Notes Forward Treasury Lock Agreements Fixed Portion Of Future Interest Cost			5-year, 10-year and 30-year notes
Number of forward treasury lock agreements terminated | Agreement										3
Collateral posted	$ 0	$ 0		$ 0	$ 0		$ 0
Amount of gains (losses) recognized in CTA on the effective portion of outstanding net investment hedges	37,000,000	10,000,000		37,000,000	10,000,000		$ 2,000,000
Gains (losses) reclassified from CTA to income for the Company's outstanding net investment hedges	0	0		0	0
Gains (losses) recognized in income for the ineffective portion of cash flow hedges	$ 0	$ 0		$ 0	$ 0
Treasury Lock
Derivative [Line Items]
Notional amount			$ 1,300,000,000
Cross-Currency Interest Rate Swaps
Derivative [Line Items]
Number of fixed to floating interest rate swaps outstanding | Swap	1	4		1	4	1	4	4	4
Notional amount | ¥						¥ 5		¥ 20	¥ 20
Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount | ¥						¥ 37		¥ 0	¥ 0
Common stock shares
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | shares	3.8	4.0		3.8	4.0	3.8	4.0	4.0	4.0