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Revenue from Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations (Detail) $ in Millions | Sep. 30, 2018 USD ($)
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Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 472.7
2018 (Remaining Three Months) [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 207.6
2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 182.0
2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 37.4
2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 14.2
2022 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 8.3
Thereafter [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 23.2
Brokerage [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 297.0
Brokerage [Member] | 2018 (Remaining Three Months) [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 157.8
Brokerage [Member] | 2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 122.8
Brokerage [Member] | 2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 13.9
Brokerage [Member] | 2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 1.3
Brokerage [Member] | 2022 [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 | 0.7
Risk Management [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 175.7
Risk Management [Member] | 2018 (Remaining Three Months) [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 49.8
Risk Management [Member] | 2019 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 59.2
Risk Management [Member] | 2020 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 23.5
Risk Management [Member] | 2021 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 12.9
Risk Management [Member] | 2022 [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | 7.8
Risk Management [Member] | Thereafter [Member] |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Expected revenue related to performance obligations | $ 22.5

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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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