Reinsurance - Summary of Reinsurance Claims Incurred and Ceded (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
Claims incurred, gross			$ 590,951	$ 452,261
Claims incurred, ceded			(483)	(1,616)
Net claims incurred and claims adjustment expense	$ 214,432	$ 146,328	$ 590,468	$ 450,645

Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
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Amount of policy benefits and costs incurred for policies assumed.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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