Acquisitions 2 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Jul. 08, 2015	Mar. 31, 2015
Business Combinations [Abstract]
Accrued acquisition-related costs related to purchase price amounts withheld to support indemnification obligations	$ 5		$ 5			$ 27
Business Acquisition
Total revenue for the fiscal year 2016 acquisitions of Rally and Xceedium	1,034	$ 1,091	3,016	$ 3,239
Net loss for the fiscal year 2016 acquisitions of Rally and Xceedium	223	$ 222	609	$ 695
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	less than $1 million
Transaction costs for fiscal year 2016 acquisitions			20
Rally and Xceedium
Business Acquisition
Total revenue for the fiscal year 2016 acquisitions of Rally and Xceedium	$ 38		63
Net loss for the fiscal year 2016 acquisitions of Rally and Xceedium	$ (22)		$ (35)