Hedging Activities - Narrative (Details) € in Millions, £ in Millions, $ in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Apr. 30, 2024 CAD ($)	Mar. 31, 2024 EUR (€)	Mar. 31, 2024 GBP (£)	Mar. 31, 2024 CAD ($)	Dec. 31, 2023 GBP (£)	Jun. 15, 2023 USD ($)	Mar. 31, 2023 EUR (€)	Mar. 31, 2023 GBP (£)	Mar. 31, 2023 CAD ($)	Feb. 28, 2023 GBP (£)	Dec. 31, 2022 GBP (£)	Mar. 31, 2022 EUR (€)
Derivative [Line Items]
Total debt		$ 5,629	$ 5,594
Gain (loss) on derivative termination			97
Cash Flow Hedging | Derivatives designated for hedge accounting: | Interest Rate Swap
Derivative [Line Items]
Notional amounts of derivative									$ 500
Derivative, notional mount, terminated			500
Derivative, notional amount, entered into during period	$ 50		450
Derivative, termination proceeds, amortization period		10 years
British Pound Sterling Denominated Notes | Loans payable
Derivative [Line Items]
Total debt | £														£ 450
EUR | Fair Value Hedges | Derivatives designated for hedge accounting: | Currency Swap
Derivative [Line Items]
Notional amounts of derivative | €					€ 1,100					€ 1,100
EUR | Currency Swap | Net Investment Hedging | Derivatives designated for hedge accounting:
Derivative [Line Items]
Notional amounts of derivative | €										1,100					€ 1,100
EUR | Currency Swap | Fair Value Hedges | Derivatives designated for hedge accounting:
Derivative [Line Items]
Notional amounts of derivative										€ 1,100			£ 450
USD | Fair Value Hedges | Derivatives designated for hedge accounting: | Interest Rate Swap Entered Into YTD
Derivative [Line Items]
Notional amounts of derivative			1,300
USD | Fair Value Hedges | Derivatives designated for hedge accounting: | Interest Rate Swap
Derivative [Line Items]
Notional amounts of derivative		$ 1,250	1,250
GBP | Fair Value Hedges | Derivatives designated for hedge accounting: | Currency Swap
Derivative [Line Items]
Notional amounts of derivative | £						£ 450					£ 450
GBP | Cash Flow Hedging | Derivatives designated for hedge accounting: | Forward Contracts
Derivative [Line Items]
Notional amounts of derivative | £						£ 39		£ 45			£ 0
CAD | Net Investment Hedging | Derivatives designated for hedge accounting: | Currency Swap
Derivative [Line Items]
Notional amounts of derivative							$ 1,500					$ 1,500
CAD | Net Investment Hedging | Derivatives designated for hedge accounting: | Currency Swap | Subsequent Event
Derivative [Line Items]
Notional amounts of derivative				$ 1,500
Derivative, notional mount, terminated				$ 500
CAD | Cash Flow Hedging | Derivatives designated for hedge accounting: | Currency Swap
Derivative [Line Items]
Notional amounts of derivative							$ 0					$ 400
Disposal Group, Disposed of by Sale, Not Discontinued Operations | European Businesses (Disposal Group)
Derivative [Line Items]
Reclassification from AOCI, current period, before tax			112
Disposal Group, Disposed of by Sale, Not Discontinued Operations | U.K. Businesses (Disposal Group)
Derivative [Line Items]
Reclassification from AOCI, current period, before tax, attributable to parent			$ 26