Statutory Information and Dividend Restrictions - Schedule of Selected Information for Insurance Subsidiaries (Details) - Insurance Subsidiaries - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Selected information for insurance subsidiaries
Consolidated net income, statutory basis	$ 207,550	$ 120,329	$ 129,625
Consolidated surplus, statutory basis	$ 1,240,649	$ 1,121,592	$ 1,029,671

The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-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 505
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant