Debt - Schedule of the Change in Debt (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Debt Instrument
Beginning balance	$ 693.0
Repayments	(14.8)	$ (93.7)
Ending balance	690.9
Kudu Credit Facility
Debt Instrument
Beginning balance	218.2
Ending balance	218.2
Term Loan \| NSM Bank Facility
Debt Instrument
Beginning balance	271.2
Ending balance	270.0
Specialty Insurance Distribution (NSM)
Debt Instrument
Beginning balance	272.1
Ending balance	270.6
Specialty Insurance Distribution (NSM) \| NSM Bank Facility
Debt Instrument
Beginning balance	277.6	277.4
Ending balance	275.9	277.3
Specialty Insurance Distribution (NSM) \| Term Loan \| NSM Bank Facility
Debt Instrument
Borrowings	0.0	0.0
Repayments	(0.7)	(0.7)
Foreign currency translation	(1.5)	0.6
Specialty Insurance Distribution (NSM) \| Revolving credit loan \| NSM Bank Facility
Debt Instrument
Borrowings	13.0	0.0
Repayments	(12.5)	0.0
Kudu \| Term Loan \| Kudu Bank Facility
Debt Instrument
Beginning balance	0.0	89.2
Borrowings	0.0	3.0
Repayments	0.0	(92.2)
Ending balance	0.0	0.0
Kudu \| Term Loan \| Kudu Credit Facility
Debt Instrument
Beginning balance	225.4	0.0
Borrowings	0.0	102.0
Repayments	0.0	0.0
Ending balance	$ 225.4	$ 102.0

Amount of increase (decrease) in debt instruments, classified as other.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
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- 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.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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