Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Segment Reporting Information [Line Items]
Income tax rate (as a percent)	(37.70%)	16.80%		(3.50%)	25.70%
Income tax expense related to continuing operations	$ (263)	$ 131		$ (46)	$ 570
Net discrete tax expense (benefit)	(424)	(12)		(420)	(69)
Discrete tax benefit resulting from expected impact of the 2017 Tax Act	370
Other discrete tax benefit related to conclusion of certain tax audits	54
Tax benefit recognized related to excess tax benefits arising from adoption of ASU 2016-09					47
Goodwill impairment charge	0	0		350	$ 290
Unrecognized tax benefits	944			944
Unrecognized tax benefits that would reduce income tax expense and the effective tax rate	833			833
Discrete net tax benefit resulting from 2017 Tax Act impact on deferred tax asset and liabilities	1,260
Discrete tax expense related to impact of the Transition Tax	434
Discrete tax expense related to the uncertainty of the effects resulting from the 2017 Tax Act	$ 452
Distribution Solutions
Segment Reporting Information [Line Items]
Goodwill impairment charge				350
Technology Solutions
Segment Reporting Information [Line Items]
Goodwill impairment charge				$ 0
Enterprise Information Solutions | Technology Solutions
Segment Reporting Information [Line Items]
Goodwill impairment charge		290	$ 290
Nondeductible goodwill impairment		$ 269
Expected
Segment Reporting Information [Line Items]
Expected blended tax rate (percent)						31.60%