XML 119 R104.htm IDEA: XBRL DOCUMENT
v3.20.4

Derivatives and Hedging Activity - Summary of Notional and Fair Values of Derivative Instruments (Detail) - USD ($) | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |  |
Notional Amount |  | $ 598,600,000 | $ 831,700,000
Derivative Assets |  | 13,700,000 | 21,200,000
Derivative Liabilities |  | 69,300,000 | 52,400,000
Interest Rate Contracts [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Notional Amount |  | 550,000,000.0 | 800,000,000.0
Interest Rate Contracts [Member] | Other current Assets [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Assets |  |  | 2,800,000
Interest Rate Contracts [Member] | Other noncurrent Assets [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Assets |  |  | 5,400,000
Interest Rate Contracts [Member] | Accrued compensation and other current liabilities [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Liabilities |  | 54,500,000 | 25,000,000.0
Interest Rate Contracts [Member] | Other noncurrent Liabilities [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Liabilities |  | 10,900,000 | 23,000,000.0
Foreign Exchange Contracts [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Notional Amount | [1] | 48,600,000 | 31,700,000
Foreign Exchange Contracts [Member] | Other current Assets [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Assets | [1] | 5,900,000 | 4,500,000
Foreign Exchange Contracts [Member] | Other noncurrent Assets [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Assets | [1] | 7,800,000 | 8,500,000
Foreign Exchange Contracts [Member] | Accrued compensation and other current liabilities [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Liabilities | [1] | 600,000 | 1,800,000
Foreign Exchange Contracts [Member] | Other noncurrent Liabilities [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Liabilities | [1] | $ 3,300,000 | $ 2,600,000
[1] | Included within foreign exchange contracts at December 31, 2020 were $354.7 million of call options offset with $354.7 million of put options, and $9.0 million of buy forwards offset with $57.6 million of sell forwards. Included within foreign exchange contracts at December 31, 2019 were $342.0 million of call options offset with $342.0 million of put options, and $12.1 million of buy forwards offset with $43.8 million of sell forwards.

X
- Definition Nominal or face amount used to calculate payments on the derivative asset. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeAssetNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nominal or face amount used to calculate payments on the derivative liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeLiabilityNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
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_DerivativesFairValueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=ajg_AccruedCompensationAndOtherCurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |