XML 73 R62.htm IDEA: XBRL DOCUMENT
v3.26.1

Deferred Compensation - Deferred Cash Participation Plan Activity (Details) - Deferred Cash Participation Plan (DCPP) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2026 | Mar. 31, 2025
Investments And Employee Deferred Compensation Plan [Line Items] |  |
Awards approved and contributed to rabbi trust | $ 6 | $ 8
Compensation expense recognized | 4 | 5
Distributions | $ 11 | $ 0

X
- Definition Cash and equity award with aggregate fair value vested and distributed to participants. + References No definition available. + Details
Name: | ajg_CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Compensation approved by committee, value + References No definition available. + Details
Name: | ajg_CompensationApprovedByCommitteeValue
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investments And Employee Deferred Compensation Plan [Line Items] + References No definition available. + Details
Name: | ajg_InvestmentsAndEmployeeDeferredCompensationPlanLineItems
Namespace Prefix: | ajg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section S45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479983/718-10-S45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=ajg_DeferredCashParticipationPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |