Acquisitions - Acquisition-related Costs (Details) - TWG Holdings Limited - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018
Business Acquisition [Line Items]
Transaction costs, incurred to date		$ 39.5
Integration costs, incurred to date		23.6
Underwriting, general and administrative expense
Business Acquisition [Line Items]
Transaction costs	$ 0.2	30.2
Integration costs	$ 10.1	$ 22.9

Business Combination, Acquisition Related Costs, Incurred to Date

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Business Combination, Integration Related Costs, Incurred to Date

+ References

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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

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e1043-128460

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Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

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