Segment and Geographical Information - Summary of Assets and Profit or Loss by Segment (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Revenues		$ 803,375	$ 688,385	$ 1,546,204	$ 1,378,422
Net investment income		38,452	32,398	76,258	63,462
Amortization of deferred policy acquisition costs		73,643	68,110	145,692	136,033
Non-cash share-based compensation expense		3,053	2,458	15,668	14,531
Income (loss) before income taxes		7,797	188,896	187,032	355,838
Assets		14,565,704		14,565,704		$ 15,027,732
Term Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Revenues		426,944	411,873	867,357	832,943
Amortization of deferred policy acquisition costs		71,916	66,004	142,407	132,072
Non-cash share-based compensation expense		954	726	3,096	2,576
Income (loss) before income taxes		147,779	140,113	286,148	270,654
Assets		6,486,934		6,486,934		6,543,923
Investment and Savings Products Segment [Member]
Segment Reporting Information [Line Items]
Revenues		260,906	214,509	504,622	424,711
Amortization of deferred policy acquisition costs		1,478	1,409	2,679	2,901
Non-cash share-based compensation expense		715	666	1,754	1,658
Income (loss) before income taxes		74,782	59,583	140,345	115,691
Assets	[1]	2,410,463		2,410,463		2,537,079
Senior Health Segment [Member]
Segment Reporting Information [Line Items]
Revenues		12,420	14,890	19,300	33,599
Non-cash share-based compensation expense		195	171	295	330
Income (loss) before income taxes		(264,972)	(6,032)	(279,125)	(9,795)
Assets		144,227		144,227		419,110
Corporate and Other Distributed Products Segment [Member]
Segment Reporting Information [Line Items]
Revenues		103,105	47,113	154,925	87,169
Net investment income		38,452	32,398	76,258	63,462
Amortization of deferred policy acquisition costs		249	697	606	1,060
Non-cash share-based compensation expense		1,189	895	10,523	9,967
Income (loss) before income taxes		50,208	$ (4,768)	39,664	$ (20,712)
Assets		$ 5,524,080		$ 5,524,080		$ 5,527,620

[1] The Investment and Savings Products segment includes assets held in separate accounts. Excluding separate accounts, the Investment and Savings Products segment assets were $156.5 million and $141.3 million as of June 30, 2024 and December 31, 2023, respectively.