Financial Instruments and Fair Value Measurements - Additional Information (Detail) (USD $)	9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Fixed Rate Debt [Member]	Sep. 30, 2013 Fixed Rate Debt [Member]	Jun. 30, 2014 Significant Observable Inputs (Level 2) [Member]	Sep. 30, 2013 Significant Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, liabilities, Level 2 to Level 1 transfers, amount	$ 0	$ 0
Fair value, assets, Level 2 to Level 1 transfers, amount	0	0
Fair value, liabilities, Level 1 to Level 2 transfers, amount	0	0
Fair value, assets, Level 1 to Level 2 transfers, amount	0	0
Fair value, assets, transfers into Level 3, amount	0	0
Fair value, assets, transfers out of Level 3, amount	0	0
Fair value, liabilities, transfers into Level 3, amount	0	0
Fair value, liabilities, transfers out of Level 3, amount	0	0
Other assets in the Consolidated Balance Sheets					14,000,000	14,000,000
Carrying value of long-term debt			958,000,000	971,000,000
Fair value of long-term debt			$ 1,010,000,000	$ 1,010,000,000