Business Acquisitions and Divestitures - Acquisition of CoverMyMeds (Details) - USD ($)		1 Months Ended		12 Months Ended
	Apr. 03, 2017	May 31, 2019	May 31, 2018	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Business Acquisition [Line Items]
Purchase consideration paid in cash, net of cash acquired				$ 35,000,000	$ 133,000,000	$ 905,000,000
CMM
Business Acquisition [Line Items]
Purchase consideration paid in cash, net of cash acquired	$ 1,300,000,000
Additional contingent consideration that may be paid	$ 160,000,000
Contingent consideration					$ 0
Cash payment for contingent consideration earned		$ 69,000,000	$ 68,000,000