Significant Accounting Policies - Accumulated Other Comprehensive Items in Accompanying Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Foreign currency translation adjustments at beginning of period	$ 154	$ 167
Net foreign currency translation adjustments during the period	(20)	(13)
Foreign currency translation adjustments at end of period	134	154
Unrealized gain on investments at beginning of period	2
Net unrealized gains during the period		2
Unrealized gain on investments at end of period	2	2
Pension and other postretirement benefit plans at beginning of period	(53)	(75)
Net change in pension and other postretirement benefit plans during the period		22
Pension and other postretirement benefit plans at end of period	(53)	(53)
Total accumulated other comprehensive income	$ 83	$ 103