Segment and Other Operating Information - Operating Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Selected Balance Sheet Items:
Total segment assets	$ 13,100,227	$ 14,330,189	$ 14,648,270
Other policyholder liabilities	175,089	134,338
Funds withheld liability	1,333,036	1,485,267
Condensed Income Statements:
Premiums and contract revenues	226,880	224,297	237,947
Net investment income	299,640	562,530	417,202
Other revenues	25,522	22,314	18,522
Realized gains on investments	6,355	14,950	21,071
Total revenues	558,397	824,091	694,742
Life and other policy benefits	159,470	187,577	131,337
Amortization of deferred transaction costs	121,398	69,461	140,503
Universal life and annuity contract interest	15,678	213,184	206,250
Other operating expenses	135,817	126,612	104,584
Federal income taxes (benefit)	24,890	46,576	19,756
Net earnings	101,144	180,681	92,312
Segments
Selected Balance Sheet Items:
Deferred transaction costs	1,249,007	892,160	691,733
Total segment assets	12,561,674	13,426,665	13,753,320
Future policy benefits	9,418,334	9,912,987	9,933,419
Other policyholder liabilities	175,089	134,338	138,480
Funds withheld liability	1,333,036	1,485,267	1,697,591
Condensed Income Statements:
Premiums and contract revenues	226,880	224,297	237,947
Net investment income	299,640	562,530	417,202
Other revenues	25,522	22,314	18,522
Total revenues	552,042	809,141	673,671
Life and other policy benefits	159,470	187,577	131,337
Amortization of deferred transaction costs	121,398	69,461	140,503
Universal life and annuity contract interest	15,678	213,184	206,250
Other operating expenses	135,817	126,612	104,584
Federal income taxes (benefit)	23,556	43,436	15,331
Total expenses	455,919	640,270	598,005
Net earnings	96,123	168,871	75,666
Segments | Domestic Life Insurance
Selected Balance Sheet Items:
Deferred transaction costs	233,460	150,688	94,100
Total segment assets	1,737,992	1,791,017	3,242,794
Future policy benefits	1,533,155	1,537,482	1,337,174
Other policyholder liabilities	25,596	20,950	16,378
Funds withheld liability	0	0	0
Condensed Income Statements:
Premiums and contract revenues	59,379	51,294	53,834
Net investment income	17,671	90,006	54,516
Other revenues	93	105	58
Total revenues	77,143	141,405	108,408
Life and other policy benefits	25,090	24,416	18,471
Amortization of deferred transaction costs	18,968	9,580	17,661
Universal life and annuity contract interest	758	77,246	44,782
Other operating expenses	31,046	26,959	25,730
Federal income taxes (benefit)	251	656	265
Total expenses	76,113	138,857	106,909
Net earnings	1,030	2,548	1,499
Segments | International Life Insurance
Selected Balance Sheet Items:
Deferred transaction costs	270,035	152,340	124,480
Total segment assets	958,699	975,942	1,034,280
Future policy benefits	678,103	749,537	798,952
Other policyholder liabilities	15,560	14,268	11,086
Funds withheld liability	0	0	0
Condensed Income Statements:
Premiums and contract revenues	76,115	79,085	88,167
Net investment income	1,681	52,227	27,273
Other revenues	71	95	67
Total revenues	77,867	131,407	115,507
Life and other policy benefits	20,777	26,481	14,084
Amortization of deferred transaction costs	19,643	(11,118)	24,929
Universal life and annuity contract interest	(3,840)	31,696	(2,087)
Other operating expenses	20,146	19,679	17,829
Federal income taxes (benefit)	4,139	13,249	9,143
Total expenses	60,865	79,987	63,898
Net earnings	17,002	51,420	51,609
Segments | Annuities
Selected Balance Sheet Items:
Deferred transaction costs	584,158	423,318	302,397
Total segment assets	8,521,636	9,187,610	7,976,588
Future policy benefits	6,409,784	6,843,457	7,028,860
Other policyholder liabilities	118,615	82,650	94,049
Funds withheld liability	1,333,036	1,485,267	1,697,591
Condensed Income Statements:
Premiums and contract revenues	15,353	16,809	17,025
Net investment income	229,324	368,234	290,576
Other revenues	6,777	5,374	43
Total revenues	251,454	390,417	307,644
Life and other policy benefits	48,029	67,515	31,043
Amortization of deferred transaction costs	73,926	61,881	87,133
Universal life and annuity contract interest	18,760	104,242	163,555
Other operating expenses	58,799	53,817	36,870
Federal income taxes (benefit)	10,169	21,094	(1,649)
Total expenses	209,683	308,549	316,952
Net earnings	41,771	81,868	(9,308)
Segments | ONL & Affiliates
Selected Balance Sheet Items:
Deferred transaction costs	161,354	165,814	170,756
Total segment assets	1,008,004	1,115,380	1,117,509
Future policy benefits	797,292	782,511	768,433
Other policyholder liabilities	15,318	16,470	16,967
Funds withheld liability	0	0	0
Condensed Income Statements:
Premiums and contract revenues	76,033	77,109	78,921
Net investment income	29,198	26,989	26,383
Other revenues	11,539	12,654	10,118
Total revenues	116,770	116,752	115,422
Life and other policy benefits	65,574	69,165	67,739
Amortization of deferred transaction costs	8,861	9,118	10,780
Universal life and annuity contract interest	0	0	0
Other operating expenses	19,579	20,244	18,454
Federal income taxes (benefit)	4,580	3,675	4,413
Total expenses	98,594	102,202	101,386
Net earnings	18,176	14,550	14,036
Segments | All Others
Selected Balance Sheet Items:
Deferred transaction costs	0	0	0
Total segment assets	335,343	356,716	382,149
Future policy benefits	0	0	0
Other policyholder liabilities	0	0	0
Funds withheld liability	0	0	0
Condensed Income Statements:
Premiums and contract revenues	0	0	0
Net investment income	21,766	25,074	18,454
Other revenues	7,042	4,086	8,236
Total revenues	28,808	29,160	26,690
Life and other policy benefits	0	0	0
Amortization of deferred transaction costs	0	0	0
Universal life and annuity contract interest	0	0	0
Other operating expenses	6,247	5,913	5,701
Federal income taxes (benefit)	4,417	4,762	3,159
Total expenses	10,664	10,675	8,860
Net earnings	18,144	18,485	17,830
Segment Reconciling Items
Condensed Income Statements:
Taxes on realized gains on investments	1,334	3,140	4,425
Realized gains on investments, net of taxes	5,021	11,810	16,646
Other unallocated
Selected Balance Sheet Items:
Total segment assets	$ 538,553	$ 903,524	$ 894,950