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Third-Party Reinsurance - Remaining Gross and Net Reinsurance Recoverables (Details) - All Entities Except TCP Providers $ in Millions	Mar. 31, 2022 USD ($)
Reinsurance [Line Items]
Reinsurance recoverables	$ 205.4
Reinsurance Recoverables, Collateral	43.4
Reinsurance Recoverables, Including Reinsurance Premium Paid	$ 162.0
Percent of reinsurance recoverables from insurers that are collateralized	100.00%
A+ or better
Reinsurance [Line Items]
Reinsurance recoverables	$ 135.5
Reinsurance Recoverables, Collateral	15.1
Reinsurance Recoverables, Including Reinsurance Premium Paid	$ 120.4
Percent of reinsurance recoverables from insurers that are collateralized	74.30%
A- to A
Reinsurance [Line Items]
Reinsurance recoverables	$ 54.6
Reinsurance Recoverables, Collateral	14.1
Reinsurance Recoverables, Including Reinsurance Premium Paid	$ 40.5
Percent of reinsurance recoverables from insurers that are collateralized	25.00%
B++ or lower and not rated
Reinsurance [Line Items]
Reinsurance recoverables	$ 15.3
Reinsurance Recoverables, Collateral	14.2
Reinsurance Recoverables, Including Reinsurance Premium Paid	$ 1.1
Percent of reinsurance recoverables from insurers that are collateralized	0.70%

X

- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(6))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

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- Definition

Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

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Percentage of Reinsurance Recoverables from Insurers, Collateralized

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