XML 70 R56.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Business Combinations - Additional Information (Detail) | 12 Months Ended | 192 Months Ended
--- | --- | ---
Dec. 31, 2017 USD ($) Entity | Dec. 31, 2016 USD ($) Entity | Dec. 31, 2015 USD ($) Entity | Dec. 31, 2017 USD ($) Entity
Business Acquisition [Line Items] |  |  |  |
Accretion of the discount on acquisition | $ 20,200,000 | $ 16,900,000 | $ 16,200,000 |
Number of companies acquired | Entity | 108 | 101 | 105 | 459
Aggregate amount of maximum earnout obligations related to acquisitions | $ 567,900,000 | $ 527,200,000 |  |
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet | 264,200,000 | 242,300,000 |  |
Income (expense) related to net adjustments to estimated fair value of liability for earnout obligations | 567,900,000 | 567,900,000 | $ 567,900,000 |
Goodwill | 304,500,000 |  |  | $ 304,500,000
Expiration lists | 241,400,000 |  |  | 241,400,000
Non-compete agreements | 3,600,000 |  |  | 3,600,000
Trade names | 100,000 |  |  | 100,000
Write-off of amortizable intangible assets | 6,200,000 | 1,800,000 | $ 11,500,000 |
Total revenues related to acquisitions in the aggregate | 6,222,800,000 | $ 5,765,900,000 |  |
Brokerage and Risk Management [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Goodwill | 304,500,000 |  |  | 304,500,000
Expiration lists | 241,400,000 |  |  | 241,400,000
Non-compete agreements | 3,600,000 |  |  | 3,600,000
Trade names | $ 100,000 |  |  | 100,000
Expiration Lists [Member] | Minimum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 3 years |  |  |
Expiration Lists [Member] | Maximum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 15 years |  |  |
Non-Compete Agreements [Member] | Minimum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 3 years |  |  |
Non-Compete Agreements [Member] | Maximum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 5 years |  |  |
Trade Names [Member] | Minimum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 5 years |  |  |
Trade Names [Member] | Maximum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of intangibles assets, years | 15 years |  |  |
2017 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Minimum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Revenue growth rate | 0.05% |  |  |
Discount rate | 0.075% |  |  |
2017 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Maximum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Revenue growth rate | 0.17% |  |  |
Discount rate | 0.09% |  |  |
2017 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Revenue growth rate | 2.00% |  |  |
Discount rate | 12.00% |  |  |
Attrition rate | 5.00% |  |  |
2017 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Revenue growth rate | 3.30% |  |  |
Discount rate | 14.00% |  |  |
Attrition rate | 10.00% |  |  |
Business Acquisition [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Annualized revenue of business acquisitions | $ 172,300,000 |  |  |
Total revenues related to acquisitions in the aggregate | 112,600,000 |  |  |
Net earnings | 4,700,000 |  |  |
Business Acquisition [Member] | Brokerage [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Expiration lists | 241,400,000 |  |  | 241,400,000
Non-compete agreements | 3,600,000 |  |  | 3,600,000
Trade names | 100,000 |  |  | 100,000
Deferred tax liability | 18,600,000 |  |  | 18,600,000
Goodwill related to nondeductible amortizable intangible assets | 18,600,000 |  |  |
Business Acquisition [Member] | Expiration Lists [Member] | Brokerage [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition not deductible for income tax purposes | 65,100,000 |  |  | 65,100,000
Business Acquisition [Member] | Non-Compete Agreements [Member] | Brokerage [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition not deductible for income tax purposes | 2,500,000 |  |  | 2,500,000
Business Acquisition [Member] | Trade Names [Member] | Brokerage [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition not deductible for income tax purposes | $ 100,000 |  |  | $ 100,000

X
- Definition Business Acquisition Purchase Price Allocation Goodwill Not Expected Tax Deductible Amount + References No definition available. + Details
Name: | ajg_BusinessAcquisitionPurchasePriceAllocationGoodwillNotExpectedTaxDeductibleAmount
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Business Acquisitions Purchase Price Allocation Goodwill Amount + References No definition available. + Details
Name: | ajg_BusinessAcquisitionsPurchasePriceAllocationGoodwillAmount
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Business Combination ,Aggregate Earnout Obligation, Maximum + References No definition available. + Details
Name: | ajg_BusinessCombinationAggregateEarnoutObligationMaximum
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Business Combination Aggregate Earnout Obligation Recorded Maximum + References No definition available. + Details
Name: | ajg_BusinessCombinationAggregateEarnoutObligationRecordedMaximum
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Business Combination, Annualize Revenue + References No definition available. + Details
Name: | ajg_BusinessCombinationAnnualizeRevenue
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Expiration lists + References No definition available. + Details
Name: | ajg_ExpirationLists
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair Value Inputs, Attrition Rate + References No definition available. + Details
Name: | ajg_FairValueInputsAttritionRate
Namespace Prefix: | ajg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Goodwill Related to Nondeductible Amortizable Intangible Assets + References No definition available. + Details
Name: | ajg_GoodwillRelatedToNondeductibleAmortizableIntangibleAssets
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after tax of pro forma income from continuing operations as if the business combination had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of deferred tax liability attributable to taxable temporary differences. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(15)(b)(2)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(26)(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(26)(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredIncomeTaxLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of assumed long-term growth in revenues, used as an input to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsLongTermRevenueGrowthRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gross carrying amount before accumulated amortization as of the balance sheet date of payments made to third parties in exchange for their agreement not to engage in specified competitive practices in specified geographic territories for a specified period of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedNoncompeteAgreementsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Gross carrying amount before accumulated amortization as of the balance sheet date of the rights acquired through registration of a trade name to gain or protect exclusive use thereof for a reasonably expected period of economic benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedTradeNamesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
Name: | us-gaap_ImpairmentOfIntangibleAssetsFinitelived
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of businesses acquired by the entity during the period. + References No definition available. + Details
Name: | us-gaap_NumberOfBusinessesAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ajg_ExpirationListsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=ajg_TwoThousandSeventeenAcquisitionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=ajg_BusinessAcquisitionMember
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: |