XML 101 R89.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Segment Information - Summary of Geographical Location and Segment (Detail) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | $ 1,837.7 | $ 1,646.4 | [1]
Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 1,195.6 | 1,084.9 |
Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 229.9 | 209.9 |
Operating Segments [Member] | Corporate [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 412.2 | 351.6 |
Unites States [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 1,457.7 | 1,327.0 |
Unites States [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 852.8 | 793.0 |
Unites States [Member] | Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 192.7 | 182.4 |
Unites States [Member] | Operating Segments [Member] | Corporate [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 412.2 | 351.6 |
United Kingdom [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 200.0 | 167.7 |
United Kingdom [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 191.0 | 161.3 |
United Kingdom [Member] | Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 9.0 | 6.4 |
Australia [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 67.3 | 59.0 |
Australia [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 43.6 | 40.3 |
Australia [Member] | Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 23.7 | 18.7 |
Canada [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 43.8 | 32.9 |
Canada [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 42.8 | 32.1 |
Canada [Member] | Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 1.0 | 0.8 |
New Zealand [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 33.6 | 28.7 |
New Zealand [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 30.1 | 27.1 |
New Zealand [Member] | Operating Segments [Member] | Risk Management [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 3.5 | 1.6 |
Other Foreign [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | 35.3 | 31.1 |
Other Foreign [Member] | Operating Segments [Member] | Brokerage [Member] |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |
Total revenues | $ 35.3 | $ 31.1 |
[1] | See Note 3 - Revenues from Contracts with Customers for additional information about the restatements related to ASC 606.

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
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: |

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

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_AU
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_NZ
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=ajg_OtherForeignMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |