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Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 37.6	$ 22.6
Lease liability	$ 38.3	$ 22.8
Weighted Average Incremental Borrowing Rate	4.60%	4.60%
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
HG/BAM
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 10.1	$ 10.4
Lease liability	10.1	10.4
NSM
Lessee, Lease, Description [Line Items]
ROU lease asset	17.1	4.8
Lease liability	17.1	4.8
Kudu
Lessee, Lease, Description [Line Items]
ROU lease asset	2.0	2.3
Lease liability	2.0	2.3
Other
Lessee, Lease, Description [Line Items]
ROU lease asset	8.4	5.1
Lease liability	$ 9.1	$ 5.3

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

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977

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- Definition

Indicates line item in statement of financial position that includes operating lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918631-209977

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977

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- Definition

Indicates line item in statement of financial position that includes operating lease right-of-use asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918631-209977

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- Definition

Weighted average discount rate for operating lease calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(4)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

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-Publisher FASB
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-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

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