Additional Financial Information - Additional Information (Detail) - USD ($)		3 Months Ended		6 Months Ended
	Dec. 02, 2016	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Supplemental Cash Flow Information [Abstract]
Accrued interest paid		$ 17,000,000	$ 34,000,000	$ 64,000,000	$ 88,000,000
Income taxes paid net of refunds		13,000,000	7,000,000	22,000,000	13,000,000
Tax refund		$ 3,000,000	$ 0	$ 3,000,000	$ 0
Special cash dividends payable, date to be paid	Jan. 03, 2017
Special cash dividends	$ 54,000,000
Special cash dividends payable, date of record	Dec. 30, 2016