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Divestitures (Details) - USD ($) $ in Millions			1 Months Ended	3 Months Ended			12 Months Ended
	Oct. 02, 2017	Jul. 18, 2017	Nov. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Aug. 01, 2017
Discontinued Operations Disclosures
Pre-tax gain on sale of business							$ 0	$ 109	$ 0
Gain from sale of equity method investment, pre-tax									$ 0
Disposal Group, Held-for-sale, Not Discontinued Operations | Enterprise Information Solutions
Discontinued Operations Disclosures
Consideration agreed upon for sale of business										$ 185
Net cash proceeds received	$ 169
Assumed net debt	$ 16
Pre-tax gain on sale of business					$ 109			$ 109
Gain from sale of business, after tax					$ 30
Other
Discontinued Operations Disclosures
Proceeds from sale of equity method investments			$ 61
Gain from sale of equity method investment, pre-tax				$ 56			$ 56
Gain from sale of equity method investment, after tax				$ 41
Net Proceeds from Sale of Equity Method Investments			23
Payments to Acquire Investments			$ 38
Distribution Solutions
Discontinued Operations Disclosures
Proceeds from sale of equity method investments		$ 42
Gain from sale of equity method investment, pre-tax						$ 43
Gain from sale of equity method investment, after tax						$ 26

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