Revenue from Contracts with Customers - Summary of Disaggregation of Revenues from Contracts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	$ 690,036	$ 691,226
Term Life Insurance Segment [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	421,069	406,983
Term Life Insurance Segment [Member] | Total Segment Revenues from Contracts with Customers [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	12,233	12,175
Term Life Insurance Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Other, Net [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	12,233	12,175
Term Life Insurance Segment [Member] | Revenues from Sources Other Than Contracts with Customers (Segregated Funds) [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	408,836	394,808
Investment and Savings Product Segment [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	210,202	241,039
Investment and Savings Product Segment [Member] | Total Segment Revenues from Contracts with Customers [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	9,909	13,744
Investment and Savings Product Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Other, Net [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	3,120	3,144
Investment and Savings Product Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Commissions and Fees [Member] | Sales-based Revenues [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	72,388	103,242
Investment and Savings Product Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Commissions and Fees [Member] | Asset-based Revenues [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	98,104	97,355
Investment and Savings Product Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Commissions and Fees [Member] | Account-based Revenues [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	22,790	21,541
Investment and Savings Product Segment [Member] | Revenues from Sources Other Than Contracts with Customers (Segregated Funds) [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	13,800	15,757
Senior Health Segment [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	18,710	5,831
Senior Health Segment [Member] | Total Segment Revenues from Contracts with Customers [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	18,710	5,831
Senior Health Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Other, Net [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	1,199	1,117
Senior Health Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Commissions and Fees [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	8,710	12,627
Corporate and Other Distributed Products Segment [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	40,055	37,373
Corporate and Other Distributed Products Segment [Member] | Total Segment Revenues from Contracts with Customers [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	196,402	225,282
Corporate and Other Distributed Products Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Other, Net [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	2,955	4,553
Corporate and Other Distributed Products Segment [Member] | Total Segment Revenues from Contracts with Customers [Member] | Commissions and Fees [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	15,755	1,278
Corporate and Other Distributed Products Segment [Member] | Revenues from Sources Other Than Contracts with Customers (Segregated Funds) [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenues from contracts with customers	$ 30,146	$ 23,629