Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Income tax expense related to continuing operations	$ 131		$ 204	$ 570	$ 704
Net discrete tax benefits	12		16	69	45
Goodwill impairment charge	$ 0		0	290	0
Non-deductible goodwill impairment charge				269
Tax benefit of non-cash pre-tax impairment charge				$ 8
Net discrete tax benefits			$ 19		$ (25)
Income tax rate (as a percent)	16.80%		24.10%	25.70%	27.30%
Unrecognized tax benefits	$ 437			$ 437
Unrecognized tax benefits that would reduce income tax expense and the effective tax rate	296			296
Income tax (benefit) expense	3		$ 3	(9)	$ 9
Accrued interest and penalties on unrecognized tax benefits	$ 43		$ 78	43	$ 78
Technology Solutions
New Accounting Pronouncement, Early Adoption [Line Items]
Goodwill impairment charge		$ 290		290
After-tax goodwill impairment		$ 282		282
Adoption of amended accounting guidance
New Accounting Pronouncement, Early Adoption [Line Items]
Tax benefit recognized related to excess tax benefits arising from adoption of ASU 2016-09				$ (47)