Recent Accounting Pronouncements (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Apr. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses	$ 2,887,000,000	$ 0	$ 2,887,000,000	$ 0
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets					$ 1,700,000,000
Lease liabilities					$ 1,800,000,000
Accounting Standards Update 2017-04
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses	2,887,000,000
GBS
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses			2,625,000,000
GBS | Accounting Standards Update 2017-04
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses	2,625,000,000
GIS
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses			$ 262,000,000
GIS | Accounting Standards Update 2017-04
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill impairment losses	$ 262,000,000