Number Of Credit Facilities

No definition available.

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Namespace Prefix:	aon_
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- Definition

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

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- 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.

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- 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.

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Balance Type:
Period Type:

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Namespace Prefix:
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Balance Type:
Period Type:

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Namespace Prefix:
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Balance Type:
Period Type:

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Balance Type:
Period Type:

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Period Type:

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Debt - Narrative (Details)	Apr. 25, 2024 USD ($)	Mar. 31, 2026 USD ($) credit_facility	Mar. 31, 2026 EUR (€) credit_facility	Jan. 31, 2026 USD ($)	Jan. 15, 2026 USD ($)	Jan. 15, 2026 EUR (€)	Dec. 31, 2025 USD ($)
Debt Instrument [Line Items]
Number of credit facilities \| credit_facility		2	2
Line of Credit
Debt Instrument [Line Items]
Line of credit facility, available credit		$ 2,000,000,000.0
Delayed draw term loan \| Line of Credit
Debt Instrument [Line Items]
Proceeds from long-term lines of credit	$ 2,000,000,000
Credit facility expiring september 2027 \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		1,000,000,000.0
Credit facility expiring october 2028 \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		1,000,000,000.0
Commercial paper
Debt Instrument [Line Items]
Commercial paper outstanding		0					$ 0
5.125% Senior Notes Due March 2027 \| Senior notes
Debt Instrument [Line Items]
Debt, face amount		$ 600,000,000
Debt interest rate percentage		5.125%	5.125%
8.205% Senior Notes due January 2027 \| Senior notes
Debt Instrument [Line Items]
Debt, face amount				$ 521,000,000
Debt interest rate percentage				8.205%
2.875% Senior Notes Due May 2026 \| Senior notes
Debt Instrument [Line Items]
Debt, face amount					$ 593,000,000	€ 500,000,000
Debt interest rate percentage					2.875%	2.875%
3.875% Senior Notes due December 2025 \| Senior notes
Debt Instrument [Line Items]
Debt, face amount							$ 750,000,000
Debt interest rate percentage							3.875%
U.S. Program \| Commercial paper
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 1,300,000,000
European Program \| Commercial paper
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 720,000,000	€ 625,000,000