XML 48 R38.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Summary of Significant Accounting Policies - Additional Information (Detail) | 9 Months Ended
--- | ---
Sep. 30, 2022 Country Segment Facility
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Number of reportable segments | Segment | 3
Number of commercial clean coal production facilities | Facility | 35
Number of countries in which the company does business through a network of correspondent brokers and consultants | Country | 130

X
- Definition Number of commercial clean coal production facilities. + References No definition available. + Details
Name: | ajg_NumberOfCommercialCleanCoalProductionFacilities
Namespace Prefix: | ajg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Countries in which the Company does Business through a Network of Correspondent Brokers and Consultants + References No definition available. + Details
Name: | ajg_NumberOfCountriesInWhichCompanyDoesBusinessThroughNetworkOfCorrespondentBrokersAndConsultants
Namespace Prefix: | ajg_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 18 -URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8672-108599 + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration