XML 50 R38.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Business Combinations - Acquisition Method for Recording Business Combinations (Detail) shares in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2017 USD ($) shares
Business Acquisition [Line Items] |
Common Shares Issued | shares | 415
Common Share Value | $ 22,100,000
Cash Paid | 300,100,000
Accrued Liability | 0
Escrow Deposited | 25,400,000
Recorded Earnout Payable | 69,400,000
Total Recorded Purchase Price | 417,000,000
Maximum Potential Earnout Payable | 146,900,000
Construction Risk Solutions, LLC [Member] |
Business Acquisition [Line Items] |
Cash Paid | 27,900,000
Accrued Liability | 0
Escrow Deposited | 3,100,000
Recorded Earnout Payable | 4,400,000
Total Recorded Purchase Price | 35,400,000
Maximum Potential Earnout Payable | 10,000,000
Hill, Chesson And Woody [Member] |
Business Acquisition [Line Items] |
Cash Paid | 34,800,000
Accrued Liability | 0
Escrow Deposited | 700,000
Recorded Earnout Payable | 15,900,000
Total Recorded Purchase Price | 51,400,000
Maximum Potential Earnout Payable | 24,400,000
Presidio Group, Inc. [Member] |
Business Acquisition [Line Items] |
Cash Paid | 41,800,000
Accrued Liability | 0
Escrow Deposited | 4,800,000
Recorded Earnout Payable | 7,000,000
Total Recorded Purchase Price | 53,600,000
Maximum Potential Earnout Payable | 15,000,000
Commercial Insurance Brokers [Member] |
Business Acquisition [Line Items] |
Cash Paid | 17,700,000
Accrued Liability | 0
Escrow Deposited | 2,000,000
Recorded Earnout Payable | 800,000
Total Recorded Purchase Price | 20,500,000
Maximum Potential Earnout Payable | $ 3,600,000
Williams - Mannny Insurance Group [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 170
Common Share Value | $ 9,800,000
Cash Paid | 28,200,000
Accrued Liability | 0
Escrow Deposited | 2,000,000
Recorded Earnout Payable | 5,400,000
Total Recorded Purchase Price | 45,400,000
Maximum Potential Earnout Payable | 11,500,000
GPL Assurance Inc. (GPL) [Member] |
Business Acquisition [Line Items] |
Cash Paid | 37,800,000
Accrued Liability | 0
Escrow Deposited | 4,200,000
Recorded Earnout Payable | 4,300,000
Total Recorded Purchase Price | 46,300,000
Maximum Potential Earnout Payable | 8,000,000
Lutgert Insurance (LI) [Member] |
Business Acquisition [Line Items] |
Cash Paid | 25,200,000
Accrued Liability | 0
Escrow Deposited | 1,300,000
Recorded Earnout Payable | 4,400,000
Total Recorded Purchase Price | 30,900,000
Maximum Potential Earnout Payable | $ 10,200,000
Twenty- three Other Acquisitions [Member] |
Business Acquisition [Line Items] |
Common Shares Issued | shares | 245
Common Share Value | $ 12,300,000
Cash Paid | 86,700,000
Accrued Liability | 0
Escrow Deposited | 7,300,000
Recorded Earnout Payable | 27,200,000
Total Recorded Purchase Price | 133,500,000
Maximum Potential Earnout Payable | $ 64,200,000

X
- Definition Business Acquisition Cost Of Acquired Entity Purchase Price Net + References No definition available. + Details
Name: | ajg_BusinessAcquisitionCostOfAcquiredEntityPurchasePriceNet
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Maximum Potential Earnout Payable + References No definition available. + Details
Name: | ajg_MaximumPotentialEarnoutPayable
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Recorded Earnout Payable + References No definition available. + Details
Name: | ajg_RecordedEarnOutPayable
Namespace Prefix: | ajg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
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 of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_EscrowDeposit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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

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

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

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

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

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

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