XML 71 R59.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations (Detail) $ in Millions | Dec. 31, 2024 USD ($)
--- | ---
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 604.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 439.2
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 95.1
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 28.2
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 17.9
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 8.9
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 15.0
Remaining performance obligation, expected timing of satisfaction, period |
Brokerage [Member] |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 430.9
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 401.1
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 26.5
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 1.8
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 0.8
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 0.4
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Brokerage [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 0.3
Remaining performance obligation, expected timing of satisfaction, period |
Risk Management [Member] |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 173.4
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 38.1
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 68.6
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 26.4
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 17.1
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 8.5
Remaining performance obligation, expected timing of satisfaction, period | 1 year
Risk Management [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01 |
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 14.7
Remaining performance obligation, expected timing of satisfaction, period |

X
- Definition Amount of transaction price allocated to performance obligation that has not been recognized as revenue. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (a) -SubTopic 10 -Topic 606 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-13 + Details
Name: | us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b)(1) -SubTopic 10 -Topic 606 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-13 + Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2025-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2026-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2027-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2028-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2029-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2030-01-01
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ajg_BrokerageSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ajg_RiskManagementSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |