XML 79 R68.htm IDEA: XBRL DOCUMENT
v3.26.1

Commitments, Contingencies and Off-Balance Sheet Arrangements - Off-Balance Sheet Commitments (Detail) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2026 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |
Amount of Commitment Expiration by Period - 2026 | $ 0
Amount of Commitment Expiration by Period - 2027 | 0
Amount of Commitment Expiration by Period - 2028 | 0
Amount of Commitment Expiration by Period - 2029 | 0
Amount of Commitment Expiration by Period - 2030 | 0
Amount of Commitment Expiration by Period - Thereafter | 63
Total Amounts Committed | 63
Financial guarantees |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |
Amount of Commitment Expiration by Period - 2026 | 0
Amount of Commitment Expiration by Period - 2027 | 0
Amount of Commitment Expiration by Period - 2028 | 0
Amount of Commitment Expiration by Period - 2029 | 0
Amount of Commitment Expiration by Period - 2030 | 0
Amount of Commitment Expiration by Period - Thereafter | 49
Total Amounts Committed | 49
Letters of credit |
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] |
Amount of Commitment Expiration by Period - 2026 | 0
Amount of Commitment Expiration by Period - 2027 | 0
Amount of Commitment Expiration by Period - 2028 | 0
Amount of Commitment Expiration by Period - 2029 | 0
Amount of Commitment Expiration by Period - 2030 | 0
Amount of Commitment Expiration by Period - Thereafter | 14
Total Amounts Committed | $ 14

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitments
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year Five + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year Four + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year One + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year Thereafter + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year Three + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Commitment Expiration Off-Balance Sheet Commitments Within Year Two + References No definition available. + Details
Name: | ajg_AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Commitments Contingencies And Off Balance Sheet Arrangements [Line Items] + References No definition available. + Details
Name: | ajg_CommitmentsContingenciesAndOffBalanceSheetArrangementsLineItems
Namespace Prefix: | ajg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_FinancialGuaranteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=ajg_LettersOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |