Business Combinations, Intangibles and Goodwill - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) acquisition	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Cash paid	$ 1,304	$ 1,771
Aggregate allocation to goodwill	17,083		$ 16,134
Virtustream
Business Acquisition [Line Items]
Aggregate consideration	1,219
Aggregate allocation to intangibles	$ 379
Weighted average amortization period of intangible assets acquired	9 years
All 2015 acquisitions excluding Virtustream
Business Acquisition [Line Items]
Aggregate consideration	$ 89
Number of Businesses Acquired | acquisition	5
Aggregate allocation to goodwill	$ 64
Aggregate allocation to intangibles	33
Aggregate allocation to net liabilities	$ (8)
Weighted average amortization period of intangible assets acquired	3 years 7 months