Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining cash equivalents	$ 1,219,000,000		$ 1,219,000,000		$ 1,277,000,000
Fair value of long-term debt	11,500,000,000		11,500,000,000		11,600,000,000
Fair value of debt reclassified from long term to short term	1,300,000,000		1,300,000,000		$ 750,000,000
Transfer of assets in and out of level 1, 2 and 3 measurements during the period	0	$ 0	0	$ 0
Transfer of liabilities in and out of level 1, 2 and 3 measurements during the period	0	$ 0	0	$ 0
Contingent consideration arrangements, decrease in contingent liability	22,000,000
Notes Due 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 500,000,000		$ 500,000,000
Debt instrument, interest rate	1.75%		1.75%
Notes Due June 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt						$ 750,000,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of short-term investments at the time of purchase			3 months
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of short-term investments at the time of purchase			1 year