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SCHEDULE I SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Millions	Dec. 31, 2020 USD ($)
Summary of investments other than investments in related parties
Cost	$ 2,062.0
Carrying Value	2,939.1
Fair Value	2,939.1
Fixed maturity investments
Summary of investments other than investments in related parties
Cost	1,151.7
Carrying Value	1,207.2
Fair Value	1,207.2
U.S. Government and agency obligations
Summary of investments other than investments in related parties
Cost	173.2
Carrying Value	176.3
Fair Value	176.3
Debt securities issued by corporations
Summary of investments other than investments in related parties
Cost	522.8
Carrying Value	547.4
Fair Value	547.4
Municipal obligations
Summary of investments other than investments in related parties
Cost	244.0
Carrying Value	265.0
Fair Value	265.0
Mortgage and asset-backed securities
Summary of investments other than investments in related parties
Cost	211.7
Carrying Value	218.5
Fair Value	218.5
Short-term investments
Summary of investments other than investments in related parties
Cost	142.9
Carrying Value	142.9
Fair Value	142.9
Other long-term investments
Summary of investments other than investments in related parties
Cost	767.4
Carrying Value	786.8
Fair Value	786.8
MediaAlpha
Summary of investments other than investments in related parties
Cost	0.0
Carrying Value	802.2
Fair Value	$ 802.2

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Amount of investment held by insurance company, excluding investment in related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column D))
-URI http://asc.fasb.org/extlink&oid=120401592&loc=d3e611379-123010

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Cost of investment held by insurance company, excluding investment in related party.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column B))
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Fair value of investment held by insurance company, excluding investment in related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column C))
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