Restructuring and Acquisition-Related Charges - Additional information (Detail) $ in Millions	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) position	Jun. 30, 2015 position	Mar. 31, 2015 position	Sep. 30, 2014 USD ($) position	Jun. 30, 2014 position	Mar. 31, 2014 position	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 position
Restructuring Cost and Reserve [Line Items]
Restructuring and acquisition-related charges	$ 68			$ 39			$ 226	$ 187
Restructuring charges	66			31			200	175
Acquisition-related charges	1			2			4	3
Lease termination costs for facilities	5			2			22	10
VMware
Restructuring Cost and Reserve [Line Items]
Restructuring charges							20
Acquisition-related charges	$ 1						$ 2	5
Restructuring Reserve, Accrual Adjustment				$ 6				$ 4
Restructuring 2015 Programs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | position	680	160	1,320
Restructuring 2015 Programs | VMware
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | position			350
Restructuring 2014 Programs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | position				240	210	1,320			2,100
Restructuring 2014 Programs | VMware
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | position				90