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Revenue from Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations (Detail) $ in Millions | Dec. 31, 2018 USD ($)
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Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 457.7
2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 349.6
2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 46.2
2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 27.5
2022 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 9.8
2023 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 5.9
Thereafter [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 18.7
Brokerage [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 284.7
Brokerage [Member] | 2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 253.2
Brokerage [Member] | 2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 17.7
Brokerage [Member] | 2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 12.1
Brokerage [Member] | 2022 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 0.8
Brokerage [Member] | 2023 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 0.5
Brokerage [Member] | Thereafter [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 0.4
Risk Management [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 173.0
Risk Management [Member] | 2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 96.4
Risk Management [Member] | 2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 28.5
Risk Management [Member] | 2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 15.4
Risk Management [Member] | 2022 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 9.0
Risk Management [Member] | 2023 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 5.4
Risk Management [Member] | Thereafter [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 18.3

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- Definition Amount of transaction price allocated to performance obligation that has not been recognized as revenue. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045 + Details
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