Nature of Operations and Significant Accounting Policies - Contractholder and Policyholder Liabilities (Details) - Individual Life insurance	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Contractholder and Policyholder Liabilities
Participating business as a percentage of life insurance in force (as a percent)	2.00%	3.00%	4.00%
Participating business as a percentage of life insurance policies in force (as a percent)	16.00%	17.00%	18.00%
Participating business as a percentage of life insurance premiums (as a percent)	16.00%	18.00%	26.00%

Percentage of participating insurance contract to insurance contracts in force.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(14)(b)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 944
-SubTopic 50
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479756/944-50-50-1

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant