XML 108 R95.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Investments - Clean Coal Investments - Additional Information (Detail) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 USD ($) Entity Plant
Chem-Mod LLC [Member] |
Schedule of Equity Method Investments [Line Items] |
Number of clean coal production plants owned | Plant | 35
Chem-Mod LLC [Member] | 2009 Era Plants [Member] |
Schedule of Equity Method Investments [Line Items] |
Number of clean coal production plants owned | Plant | 14
Chem-Mod LLC [Member] | 2011 Era Plants [Member] |
Schedule of Equity Method Investments [Line Items] |
Number of clean coal production plants owned | Plant | 21
Clean-Coal Investments [Member] |
Schedule of Equity Method Investments [Line Items] |
Number of variable interest entities | Entity | 1
Clean-Coal Investments [Member] | VIE [Member] |
Schedule of Equity Method Investments [Line Items] |
Total assets of limited liability companies | $ 41.7
Total liability of limited liability companies | 41.7
Total revenues of limited liability companies | 86.1
Total expenses of limited liability companies | $ 104.6

X
- Definition Equity Method Investment Total Assets Of Limited Liability Companies + References No definition available. + Details
Name: | ajg_EquityMethodInvestmentAssetsOfLimitedLiabilityCompanies
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Equity Method Investment Total Expenses Of Limited Liability Companies. + References No definition available. + Details
Name: | ajg_EquityMethodInvestmentExpensesOfLimitedLiabilityCompanies
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Equity Method Investment Total Liabilities Of Limited Liability Companies. + References No definition available. + Details
Name: | ajg_EquityMethodInvestmentLiabilitiesOfLimitedLiabilityCompanies
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Equity Method Investment Total Revenues Of Limited Liability Companies. + References No definition available. + Details
Name: | ajg_EquityMethodInvestmentRevenuesOfLimitedLiabilityCompanies
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of clean coal production plants owned + References No definition available. + Details
Name: | ajg_NumberOfCleanCoalProductionPlantsOwned
Namespace Prefix: | ajg_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Variable Interest Entities + References No definition available. + Details
Name: | ajg_NumberOfVariableInterestEntities
Namespace Prefix: | ajg_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- 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
Name: | us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ajg_ChemModLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ajg_TwoThousandNineEraPlantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ajg_TwoThousandElevenEraPlantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ajg_CleanCoalInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |