Goodwill, Capitalized Software and Other Intangible Assets 1 (Details) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017
Capitalized software and other intangible assets
Gross amortizable assets	$ 9,254	$ 9,156
Less: Fully amortized assets	7,080	6,755
Remaining amortizable assets	2,174	2,401
Accumulated amortization on remaining amortizable assets	998	1,094
Net assets	1,176	1,307
Purchased Software Products
Capitalized software and other intangible assets
Gross amortizable assets	6,565	6,496
Less: Fully amortized assets	4,910	4,914
Remaining amortizable assets	1,655	1,582
Accumulated amortization on remaining amortizable assets	837	667
Net assets	818	915
Internally Developed Software Products
Capitalized software and other intangible assets
Gross amortizable assets	1,467	1,467
Less: Fully amortized assets	1,347	1,029
Remaining amortizable assets	120	438
Accumulated amortization on remaining amortizable assets	103	391
Net assets	17	47
Other Intangible Assets
Capitalized software and other intangible assets
Gross amortizable assets	1,222	1,193
Less: Fully amortized assets	823	812
Remaining amortizable assets	399	381
Accumulated amortization on remaining amortizable assets	58	36
Net assets	$ 341	$ 345