Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining cash equivalents	$ 1,191,000,000		$ 1,277,000,000
Fair value of long-term debt	11,100,000,000		11,600,000,000
Fair value of debt reclassified from long term to short term	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
Transfer of liabilities in and out of level 1, 2 and 3 measurements during the period	$ 0	$ 0
Notes Due June 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt				$ 750,000,000
Notes Due 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, interest rate	1.75%
Fair value of debt	$ 500,000,000
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