Statutory Accounting and Regulatory Requirements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2022
Insurance [Abstract]
Dividends to the Company	10.00%
Dividends paid	$ 148.4	$ 88.6	$ 115.9
Dividends permissible to pay without seeking regulatory approval				$ 77.8

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585

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Balance Type:	credit
Period Type:	duration