XML 75 R63.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Credit and Other Debt Agreements - Summary of Corporate and Other Debt (Parenthetical) (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 | Dec. 31, 2017
Fixed Rate of 2.80%, Balloon Due June 24, 2018 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 2.80% | 2.80%
Periodic payments of interest and principal, expiry date | Jun. 24, 2018 | Jun. 24, 2018
Fixed Rate of 5.85%, $50 Million Due November 30, 2018 and November 30, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 5.85% | 5.85%
Long-Term debt maturities repayments in 2018 | $ 50.0 | $ 50.0
Long-Term debt maturities repayments in 2019 | $ 50.0 | $ 50.0
Fixed Rate of 3.20%, Balloon Due June 24, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 3.20% | 3.20%
Periodic payments of interest and principal, expiry date | Jun. 24, 2019 | Jun. 24, 2019
Fixed Rate of 3.48%, Balloon Due June 24, 2020 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 3.48% | 3.48%
Periodic payments of interest and principal, expiry date | Jun. 24, 2020 | Jun. 24, 2020
Fixed Rate of 3.99%, Balloon Due July 10, 2020 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 3.99% | 3.99%
Periodic payments of interest and principal, expiry date | Jul. 10, 2020 | Jul. 10, 2020
Fixed Rate of 5.18%, Balloon Due February 10, 2021 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 5.18% | 5.18%
Periodic payments of interest and principal, expiry date | Feb. 10, 2021 | Feb. 10, 2021
Fixed Rate of 3.69%, Balloon Due June 14, 2022 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 3.69% | 3.69%
Periodic payments of interest and principal, expiry date | Jun. 14, 2022 | Jun. 14, 2022
Fixed Rate of 5.49%, Balloon Due February 10, 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 5.49% | 5.49%
Periodic payments of interest and principal, expiry date | Feb. 10, 2023 | Feb. 10, 2023
Fixed Rate of 4.13%, Balloon Due June 24, 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.13% | 4.13%
Periodic payments of interest and principal, expiry date | Jun. 24, 2023 | Jun. 24, 2023
Floating Rate of 1.65% LIBOR Plus Balloon Due August 2, 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Quarterly payments of interest rate | 1.65% | 1.65%
Periodic payments of interest and principal, expiry date | Aug. 02, 2023 | Aug. 02, 2023
Quarterly payments of interest, description | 90 day LIBOR plus | 90 day LIBOR plus
Fixed Rate of 4.58%, Balloon Due February 27, 2024 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.58% | 4.58%
Periodic payments of interest and principal, expiry date | Feb. 27, 2024 | Feb. 27, 2024
Fixed Rate of 4.31%, Balloon Due June 24, 2025 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.31% | 4.31%
Periodic payments of interest and principal, expiry date | Jun. 24, 2025 | Jun. 24, 2025
Fixed Rate of 4.73%, Balloon Due February 27, 2026 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.73% | 4.73%
Periodic payments of interest and principal, expiry date | Feb. 27, 2026 | Feb. 27, 2026
Fixed Rate of 4.40%, Balloon Due June 2, 2026 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.40% | 4.40%
Periodic payments of interest and principal, expiry date | Jun. 02, 2026 | Jun. 02, 2026
Fixed Rate of 4.36%, Balloon Due June 24, 2026 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.36% | 4.36%
Periodic payments of interest and principal, expiry date | Jun. 24, 2026 | Jun. 24, 2026
Fixed Rate of 4.09%, Balloon Due June 27, 2027 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.09% | 4.09%
Periodic payments of interest and principal, expiry date | Jun. 27, 2027 | Jun. 27, 2027
Fixed Rate of 4.09%, Balloon Due August 2, 2027 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.09% | 4.09%
Periodic payments of interest and principal, expiry date | Aug. 02, 2027 | Aug. 02, 2027
Fixed Rate of 4.14%, Balloon Due August 4, 2027 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.14% | 4.14%
Periodic payments of interest and principal, expiry date | Aug. 04, 2027 | Aug. 04, 2027
Fixed Rate of 3.46%, Balloon Due December 1, 2027 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 3.46% | 3.46%
Periodic payments of interest and principal, expiry date | Dec. 01, 2027 | Dec. 01, 2027
Fixed Rate of 4.55%, Balloon Due June 2, 2028 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.55% | 4.55%
Periodic payments of interest and principal, expiry date | Jun. 02, 2028 | Jun. 02, 2028
Fixed Rate of 4.98%, Balloon Due February 27, 2029 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.98% | 4.98%
Periodic payments of interest and principal, expiry date | Feb. 27, 2029 | Feb. 27, 2029
Fixed Rate of 4.19%, Balloon Due June 27, 2029 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.19% | 4.19%
Periodic payments of interest and principal, expiry date | Jun. 27, 2029 | Jun. 27, 2029
Fixed Rate of 4.19%, Balloon Due August 2, 2029 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.19% | 4.19%
Periodic payments of interest and principal, expiry date | Aug. 02, 2029 | Aug. 02, 2029
Fixed Rate of 4.70%, Balloon Due June 2, 2031 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.70% | 4.70%
Periodic payments of interest and principal, expiry date | Jun. 02, 2031 | Jun. 02, 2031
Fixed Rate of 4.34%, Balloon Due June 27, 2032 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.34% | 4.34%
Periodic payments of interest and principal, expiry date | Jun. 27, 2032 | Jun. 27, 2032
Fixed Rate of 4.34%, Balloon Due August 2, 2032 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 4.34% | 4.34%
Periodic payments of interest and principal, expiry date | Aug. 02, 2032 | Aug. 02, 2032
Prime or LIBOR Plus up to 1.45%, Expires April 8, 2021 [Member] | Credit Agreement [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 1.45% | 1.45%
Periodic payments of interest and principal, expiry date | Apr. 08, 2021 | Apr. 08, 2021
Premium Financing Debt Facility [Member] |  |
Debt Instrument [Line Items] |  |
Periodic payments of interest and principal, expiry date | May 18, 2019 | May 18, 2019
First Installment [Member] | Fixed Rate of 5.85%, $50 Million Due November 30, 2018 and November 30, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic payments of interest and principal, expiry date | Nov. 30, 2018 | Nov. 30, 2018
Second Installment [Member] | Fixed Rate of 5.85%, $50 Million Due November 30, 2018 and November 30, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic payments of interest and principal, expiry date | Nov. 30, 2019 | Nov. 30, 2019
Facility B [Member] | Premium Financing Debt Facility [Member] | Interbank Rates Plus 1.05%, Expires May 18, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 1.05% | 1.05%
Facility C and D [Member] | Premium Financing Debt Facility [Member] | Interbank Rates Plus 0.55%, Expires May 18, 2019 [Member] |  |
Debt Instrument [Line Items] |  |
Periodic Payment of Interest | 0.55% | 0.55%

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfTwoPointEightZeroPercentBalloonDueJuneTwentyFourTwoThousandEighteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFivePointEightFivePercentFiftyMillionDollarsDueNovemberThirtyTwoThousandEighteenAndNovemberThirtyTwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfThreePointTwoZeroPercentBalloonDueJuneTwentyFourTwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfThreePointFourEightPercentBalloonDueJuneTwentyFourTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfThreePointNineNinePercentBalloonDueJulyTenTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFivePointOneEightPercentBalloonDueFebruaryTenTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfThreePointSixNinePercentBalloonDueJuneFourteenTwoThousandTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFivePointFourNinePercentBalloonDueFebruaryTenTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointOneThreePercentageBalloonDueJuneTwentyFourTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FloatingInterestRateOfOnePointOneSixFivePercentLIBORPlusBalloonDueAugustTwoTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointFiveEightPercentBalloonDueFebruaryTwentySevenTwoThousandTwentyFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointThreeOnePercentBalloonDueJuneTwentyFourTwoThousandTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointSevenThreePercentBalloonDueFebruaryTwentySevenTwoThousandTwentySixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointFourZeroPercentBalloonDueJuneTwoTwoThousandTwentySixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointThreeSixPercentBalloonDueJuneTwentyFourTwoThousandTwentySixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointZeroNinePercentBalloonDueJuneTwentySevenTwoThousandTwentySevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointZeroNinePercentBalloonDueAugustTwoTwoThousandTwentySevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointOneFourPercentBalloonDueAugustFourTwoThousandTwentySevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfThreePointFourSixPercentageBalloonDueDecemberOneTwoThousandTwentySevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointFiveFivePercentBalloonDueJuneTwoTwoThousandTwentyEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointNineEightPercentBalloonDueFebruaryTwentySevenTwoThousandTwentyNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointOneNinePercentBalloonDueJuneTwentySevenTwoThousandTwentyNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointOneNinePercentBalloonDueAugustTwoTwoThousandTwentyNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointSevenZeroPercentBalloonDueJuneTwoTwoThousandThirtyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointThreeFourPercentBalloonDueJuneTwentySevenTwoThousandThirtyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_FixedRateOfFourPointThreeFourPercentBalloonDueAugustTwoTwoThousandThirtyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_PrimeOrLiborPlusUpToOnePointFourFivePercentExpiresAprilEightTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=ajg_CreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtSecurityAxis=ajg_PremiumFinancingDebtFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ajg_FirstInstallmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ajg_SecondInstallmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ajg_FacilityBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_InterbankRatesPlusOnePointZeroFivePercentExpiresMayEighteenTwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ajg_FacilityAndFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExtinguishmentOfDebtAxis=ajg_InterbankRatesPlusZeroPointFiveFivePercentExpiresMayEighteenTwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |