Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

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Balance Type:	credit
Period Type:	duration

Debt - Narrative (Details) $ in Millions		1 Months Ended				3 Months Ended							9 Months Ended	12 Months Ended
Debt - Narrative (Details) $ in Millions	Mar. 16, 2021 USD ($)	Oct. 31, 2020 USD ($)	Oct. 31, 2020 GBP (£)	Oct. 31, 2020 EUR (€)	Oct. 31, 2020 AUD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 GBP (£)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 GBP (£)	Jun. 30, 2020 EUR (€)	Jun. 30, 2020 AUD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2021 GBP (£)	Mar. 31, 2021 EUR (€)
Debt Instrument [Line Items]
Repayments of debt		$ 3,500,000,000												$ 3,552,000,000	$ 1,039,000,000	$ 2,625,000,000
Commercial paper
Debt Instrument [Line Items]
Repayments of debt		772,000,000	£ 600,000,000
Maximum borrowing capacity \| €																		€ 1,000,000,000
Loans payable
Debt Instrument [Line Items]
Repayments of debt							$ 1,441,000,000
Revolving credit facility \| Line of credit
Debt Instrument [Line Items]
Repayments of debt		1,250,000,000											$ 4,000,000,000.0
Proceeds from debt issuance									$ 2,500,000,000
Maximum borrowing capacity									4,000,000,000.0
Senior Notes Due 2024 and 2026 \| Senior notes
Debt Instrument [Line Items]
Face amount									1,000,000,000.0
Senior Notes Due 2025 \| Senior notes
Debt Instrument [Line Items]
Face amount \| £																	£ 250,000,000
Effective interest rate						2.75%								2.75%			2.75%	2.75%
Senior Notes, Due 2024 \| Senior notes
Debt Instrument [Line Items]
Face amount									$ 500,000,000
Effective interest rate									4.00%
Repayments of debt						$ 500,000,000
Senior Notes, Due 2026 \| Senior notes
Debt Instrument [Line Items]
Face amount						$ 500,000,000			$ 500,000,000					$ 500,000,000
Effective interest rate						4.13%			4.13%					4.13%			4.13%	4.13%
Term Loan Payable, EUR, Due 2023 \| Loans payable
Debt Instrument [Line Items]
Repayments of debt \| €											€ 500,000,000
Term Loan Payable, GBP, Due 2022 \| Loans payable
Debt Instrument [Line Items]
Repayments of debt \| £								£ 300,000,000		£ 150,000,000
Term Loan Payable, AUD, Due 2022 \| Loans payable
Debt Instrument [Line Items]
Repayments of debt		358,000,000			$ 500							$ 300
Term Loan Payable, USD, Due 2025 \| Loans payable
Debt Instrument [Line Items]
Repayments of debt		381,000,000							$ 100,000,000
Senior Notes, Due 2026 \| Senior notes
Debt Instrument [Line Items]
Face amount \| €																		€ 650,000,000
Senior Notes Due 2023 \| Senior notes
Debt Instrument [Line Items]
Face amount						$ 274,000,000								$ 274,000,000
Effective interest rate	4.45%					4.45%								4.45%			4.45%	4.45%
Repayments of debt	$ 121,000,000
Senior Notes, Due 2023 \| Senior notes
Debt Instrument [Line Items]
Face amount						$ 171,000,000								$ 171,000,000
Effective interest rate	4.45%					4.45%								4.45%			4.45%	4.45%
Repayments of debt	$ 6,000,000
Term Loan Payable, EUR, Due 2024 \| Loans payable
Debt Instrument [Line Items]
Repayments of debt		410,000,000		€ 350,000,000
Term Loan Payable, EUR, Due 2022-2023 \| Loans payable
Debt Instrument [Line Items]
Effective interest rate						0.65%								0.65%			0.65%	0.65%
Repayments of debt		$ 292,000,000		€ 250,000,000