Segment and Other Operating Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	$ 12,391,731		$ 12,391,731		$ 12,553,447
Other policyholder liabilities	135,870		135,870		127,607
Condensed Consolidated Income Statements:
Premiums and contract revenues	59,610	$ 60,720	118,438	$ 116,256
Net investment income (loss)	145,694	128,424	132,215	279,755
Other revenues	7,586	3,966	11,240	10,379
Total revenues	216,015	192,685	268,503	410,594
Life and other policy benefits	33,431	33,657	67,065	61,846
Amortization of deferred policy acquisition costs and value of business acquired	31,100	31,411	61,137	63,575
Universal life and annuity contract interest	61,772	60,139	33,746	141,055
Other operating expenses	29,154	25,334	48,976	51,383
Total condensed consolidated Federal income taxes	12,145	8,448	11,228	18,841
Net earnings (loss)	48,413	33,696	46,351	73,894
Realized gains (losses) on investments	3,125	(425)	6,610	4,204
Segments
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	908,660		908,660		966,402
Total segment assets	11,744,823		11,744,823		12,092,796
Future policy benefits	9,886,120		9,886,120		10,141,971
Other policyholder liabilities	135,870		135,870		127,607
Condensed Consolidated Income Statements:
Premiums and contract revenues	59,610	60,720	118,438	116,256
Net investment income (loss)	145,694	128,424	132,215	279,755
Other revenues	7,586	3,966	11,240	10,379
Total revenues	212,890	193,110	261,893	406,390
Life and other policy benefits	33,431	33,657	67,065	61,846
Amortization of deferred policy acquisition costs and value of business acquired	31,100	31,411	61,137	63,575
Universal life and annuity contract interest	61,772	60,139	33,746	141,055
Other operating expenses	29,154	25,334	48,976	51,383
Total condensed consolidated Federal income taxes	11,489	8,537	9,840	17,958
Total expenses	166,946	159,078	220,764	335,817
Net earnings (loss)	45,944	34,032	41,129	70,573
Segments | Domestic Life Insurance
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	130,961		130,961		127,557
Total segment assets	1,419,575		1,419,575		1,399,818
Future policy benefits	1,229,105		1,229,105		1,198,103
Other policyholder liabilities	14,544		14,544		18,016
Condensed Consolidated Income Statements:
Premiums and contract revenues	12,009	10,706	23,237	21,510
Net investment income (loss)	21,475	14,995	2,092	38,494
Other revenues	1	20	30	64
Total revenues	33,485	25,721	25,359	60,068
Life and other policy benefits	4,169	3,829	10,046	7,751
Amortization of deferred policy acquisition costs and value of business acquired	3,209	3,307	5,782	6,717
Universal life and annuity contract interest	19,172	12,985	(2,521)	34,426
Other operating expenses	5,643	5,017	9,938	9,140
Total condensed consolidated Federal income taxes	172	89	360	413
Total expenses	32,365	25,227	23,605	58,447
Net earnings (loss)	1,120	494	1,754	1,621
Segments | International Life Insurance
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	192,498		192,498		209,858
Total segment assets	1,086,774		1,086,774		1,153,105
Future policy benefits	827,711		827,711		870,461
Other policyholder liabilities	12,150		12,150		14,903
Condensed Consolidated Income Statements:
Premiums and contract revenues	23,061	23,777	45,928	49,840
Net investment income (loss)	11,153	9,276	2,153	23,293
Other revenues	(6)	33	48	54
Total revenues	34,208	33,086	48,129	73,187
Life and other policy benefits	3,684	2,959	7,015	5,121
Amortization of deferred policy acquisition costs and value of business acquired	6,844	6,948	12,896	14,242
Universal life and annuity contract interest	9,492	7,337	(1,345)	19,330
Other operating expenses	4,517	4,521	7,613	8,785
Total condensed consolidated Federal income taxes	934	2,014	3,738	5,222
Total expenses	25,471	23,779	29,917	52,700
Net earnings (loss)	8,737	9,307	18,212	20,487
Segments | Annuities
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	444,772		444,772		486,553
Total segment assets	7,867,906		7,867,906		8,198,730
Future policy benefits	7,113,037		7,113,037		7,366,894
Other policyholder liabilities	94,190		94,190		80,002
Condensed Consolidated Income Statements:
Premiums and contract revenues	4,699	5,857	9,349	10,725
Net investment income (loss)	97,666	89,572	108,297	192,726
Other revenues	(8)	64	(4)	72
Total revenues	102,357	95,493	117,642	203,523
Life and other policy benefits	8,880	9,876	17,069	21,306
Amortization of deferred policy acquisition costs and value of business acquired	19,344	18,750	38,365	38,462
Universal life and annuity contract interest	33,108	39,817	37,612	87,299
Other operating expenses	12,715	9,374	19,582	16,882
Total condensed consolidated Federal income taxes	6,173	3,155	854	8,038
Total expenses	80,220	80,972	113,482	171,987
Net earnings (loss)	22,137	14,521	4,160	31,536
Segments | Acquired Businesses
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	140,429		140,429		142,434
Total segment assets	1,006,618		1,006,618		978,243
Future policy benefits	716,267		716,267		706,513
Other policyholder liabilities	14,986		14,986		14,686
Condensed Consolidated Income Statements:
Premiums and contract revenues	19,841	20,380	39,924	34,181
Net investment income (loss)	6,549	6,007	12,850	9,983
Other revenues	2,319	2,290	4,741	3,731
Total revenues	28,709	28,677	57,515	47,895
Life and other policy benefits	16,698	16,993	32,935	27,668
Amortization of deferred policy acquisition costs and value of business acquired	1,703	2,406	4,094	4,154
Universal life and annuity contract interest	0	0	0	0
Other operating expenses	4,794	4,491	8,863	7,576
Total condensed consolidated Federal income taxes	1,918	956	3,140	1,703
Total expenses	25,113	24,846	49,032	41,101
Net earnings (loss)	3,596	3,831	8,483	6,794
Segments | All Others
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs, sales inducements, and value of business acquired	0		0		0
Total segment assets	363,950		363,950		362,900
Future policy benefits	0		0		0
Other policyholder liabilities	0		0		0
Condensed Consolidated Income Statements:
Premiums and contract revenues	0	0	0	0
Net investment income (loss)	8,851	8,574	6,823	15,259
Other revenues	5,280	1,559	6,425	6,458
Total revenues	14,131	10,133	13,248	21,717
Life and other policy benefits	0	0	0	0
Amortization of deferred policy acquisition costs and value of business acquired	0	0	0	0
Universal life and annuity contract interest	0	0	0	0
Other operating expenses	1,485	1,931	2,980	9,000
Total condensed consolidated Federal income taxes	2,292	2,323	1,748	2,582
Total expenses	3,777	4,254	4,728	11,582
Net earnings (loss)	10,354	5,879	8,520	10,135
Other unallocated
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	646,908		646,908		460,651
Segment Reconciling Items
Condensed Consolidated Income Statements:
Taxes on realized gains (losses) on investments	656	(89)	1,388	883
Realized gains (losses) on investments, net of taxes	$ 2,469	$ (336)	$ 5,222	$ 3,321
Restatement Adjustment
Selected Condensed Consolidated Balance Sheet Items:
Future policy benefits					$ 15,000