Acquisitions 2 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jul. 08, 2015	Mar. 31, 2015
Business Combinations [Abstract]
Accrued acquisition-related costs related to purchase price amounts withheld to support indemnification obligations	$ 7		$ 7			$ 27
Business Acquisition
Total revenue for the fiscal year 2016 acquisitions of Rally and Xceedium	1,005	$ 1,079	1,982	$ 2,148
Net loss for the fiscal year 2016 acquisitions of Rally and Xceedium	174	$ 256	386	$ 473
Rally
Business Acquisition
Percentage of outstanding shares of Rally common stock acquired					100.00%
Purchase price for Rally	519		519		$ 519
Fiscal Year 2016 Acquisitions | General and Administrative
Business Acquisition
Transaction costs for fiscal year 2016 acquisitions	17		20
Rally and Xceedium
Business Acquisition
Total revenue for the fiscal year 2016 acquisitions of Rally and Xceedium	25		25
Net loss for the fiscal year 2016 acquisitions of Rally and Xceedium	$ (13)		$ (13)