Healthcare Technology Net Asset Exchange (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 01, 2017	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Schedule of Equity Method Investments [Line Items]
Pre-tax gain on sale of business				$ (94)	$ 103	$ 0
Carrying value of equity method investments		$ 4,063	$ 4,063	4,063	$ 0
Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments		4,063	4,063	4,063
Excess of carrying value over proportionate share of investment net assets		4,762	4,762	4,762
Change Healthcare Long-term Debt | Change
Schedule of Equity Method Investments [Line Items]
Aggregate principal amount	$ 6,100
Core MTS Businesses | Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership interest in Joint Venture (percent)	70.00%
Core MTS Businesses | Technology Solutions | Operating Segments
Schedule of Equity Method Investments [Line Items]
Pre-tax gain on sale of business			3,947	$ 3,947
Gain from sale of business, after tax			$ 3,018
Carrying value of disposition of net assets	$ 1,132
Promissory notes contributed	1,258
Proceeds from promissory notes repaid	$ 1,258
Transition Services Agreements (“TSA”) | Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Entitled payment percentage per the ancillary agreement (percent)	1.00%
Minimum | Core MTS Businesses | Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Proportionate share of transaction expenses incurred		80
Maximum | Core MTS Businesses | Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Proportionate share of transaction expenses incurred		$ 120
Change Healthcare | Change
Schedule of Equity Method Investments [Line Items]
Direct transaction expenses incurred	$ 1,750
Repayments of Debt	2,800
Tax Receivable Agreement (“TRA”) | Change Healthcare
Schedule of Equity Method Investments [Line Items]
Noncurrent liability	$ 136