Divestitures 2 (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Sep. 30, 2014	Mar. 31, 2016	Mar. 31, 2015
Additional Disclosures by Disposal Groups, Including Discontinued Operations
Goodwill written off related to sale of discontinued component			$ 36	$ 109
ERwin
Additional Disclosures by Disposal Groups, Including Discontinued Operations
Proceeds from sale of discontinued component	$ 50
Gain (loss) on disposal of discontinued component, net of tax	4
Tax expense related to gain on disposal of discontinued component	24
Goodwill written off related to sale of discontinued component	36
Prior Period Divestiture
Additional Disclosures by Disposal Groups, Including Discontinued Operations
Gain (loss) on disposal of discontinued component, net of tax	$ (2)
Arcserve
Additional Disclosures by Disposal Groups, Including Discontinued Operations
Proceeds from sale of discontinued component		$ 170
Gain (loss) on disposal of discontinued component, net of tax		20
Tax expense related to gain on disposal of discontinued component		77
Goodwill written off related to sale of discontinued component		$ 109