Derivative and Hedging Activities - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) counterparty	Dec. 31, 2019 USD ($)	Mar. 31, 2020 USD ($)
Derivative [Line Items]
Foreign currency cash flow hedge gain (loss) to be reclassified during next 12 months	$ 2		$ 2
Number of counterparties with concentration of credit risk | counterparty			7
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency forward contracts
Derivative [Line Items]
Notational amount of derivative	507		$ 507		$ 455
Designated as Hedging Instrument | Net Investment Hedging
Derivative [Line Items]
Pretax gain (loss) on derivative instruments	0	$ 0	(6)	$ 18
Designated as Hedging Instrument | Net Investment Hedging | Foreign currency denominated debt
Derivative [Line Items]
Notational amount of derivative	800		800		1,900
Pretax gain (loss) on derivatives designated for hedge accounting included other comprehensive loss	(36)		(125)
Not Designated as Hedging Instrument | Foreign currency forward contracts
Derivative [Line Items]
Notational amount of derivative	$ 1,700		$ 1,700		$ 2,200