Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		$ 62
Charged to expense		85
Cash payments		(32)
Non-cash settlements		(15)
Other adjustments		(48)
Balance at December 31, 2015	$ 52	52
Write-off of assets relating to the sale of a business	28
Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		62
Charged to expense		11
Cash payments		(21)
Non-cash settlements		0
Other adjustments		0
Balance at December 31, 2015	52	52
Share-based Compensation
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		0
Charged to expense		15
Cash payments		0
Non-cash settlements		(15)
Other adjustments		0
Balance at December 31, 2015	0	0
Other
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		0
Charged to expense		59
Cash payments		(11)
Non-cash settlements		0
Other adjustments		(48)
Balance at December 31, 2015	$ 0	$ 0