Consolidation and Basis of Presentation - Condensed Consolidated Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Deferred policy acquisition costs	$ 644,933	$ 699,432	$ 644,933	$ 699,432	$ 663,882	$ 704,353	$ 695,875
Deferred sales inducements	78,209	102,453	78,209	102,453	85,303	102,976	96,378
Value of business acquired	134,097	143,000	134,097	143,000	138,495	149,408
Market risk benefit assets	40,073	42,358	40,073	42,358	48,759
Deferred federal income tax asset	13,822		13,822		9,032
Amounts recoverable from reinsurer, net of allowance for credit losses	1,611,143		1,611,143		1,688,788
Other assets	109,351		109,351		110,691
Total assets	12,454,386		12,454,386		12,782,945
Future policyholder obligations:
Universal life and annuity contracts					0
Traditional life reserves					0
Liability for policyholder account balances	7,285,129	7,964,609	7,285,129	7,964,609	7,661,785	8,220,944	$ 8,378,037
Additional liability for benefits in excess of account balance	151,787		151,787		148,708
Liability for future policy benefits	908,212		908,212		900,146
Market risk benefits liability	248,876	219,116	248,876	219,116	215,777
Other liabilities	190,755		190,755		157,482
Total liabilities	10,176,186		10,176,186		10,592,023
STOCKHOLDERS’ EQUITY:
Accumulated other comprehensive income (loss)	(432,879)		(432,879)		(478,219)
Retained earnings	2,669,327		2,669,327		2,627,389
Total stockholders’ equity	2,278,200	2,263,175	2,278,200	2,263,175	2,190,922	2,721,553
Total liabilities and stockholders' equity	12,454,386		12,454,386		12,782,945
Premiums and other revenues:
Universal life and annuity contract charges	37,124	32,821	72,481	65,618
Traditional life and SPIAWLC premiums	21,228	22,641	42,804	48,782
Total revenues	186,177	118,280	338,791	256,533
Benefits and expenses:
Life and other policy benefits	32,688	26,201	56,878	59,713
Market risk benefits expense	(788)	(55,492)	36,172	(116,498)
Deferred transaction costs	22,000	22,500	43,274	45,936
Universal life and annuity contract interest	32,947	(26,198)	63,159	(39,769)
Total benefits and expenses	149,290	(2,667)	286,609	12,285
Federal income taxes	7,253	24,420	10,244	50,159
Net earnings	29,634	96,527	41,938	194,089
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		2,459,448	2,190,922	2,721,553
Net earnings (loss)	29,634	96,527	41,938	194,089
Other comprehensive income (loss), net of income tax	(71,596)	(368,775)	53,605	(807,191)
Change during period	(57,665)	(292,800)	45,340	(652,467)
Total stockholders’ equity, end of period	2,278,200	2,263,175	2,278,200	2,263,175
Cash flows from operating activities:
Net earnings	29,634	96,527	41,938	194,089
Universal life and annuity contract interest	32,947	(26,198)	63,159	(39,769)
(Increase) decrease in deferred policy acquisition and sales inducement costs, and value of business acquired			30,441	11,852
(Increase) decrease in reinsurance recoverable			77,645	131,373
(Increase) decrease in other assets (Note 1)			(14,493)	443
Increase (decrease) in liabilities for future policy benefits			21,730	(15,654)
Increase (decrease) in market risk benefits liability			41,785	(123,075)
Increase (decrease) in deferred Federal income tax			(16,844)	47,245
Increase (decrease) in other liabilities (Note 1)			34,486	(12,478)
Net cash provided by operating activities			118,339	138,063
Cash flows from financing activities:
Deposits to account balances for universal life and annuity contracts (Note 1)			52,142	205,775
Return of account balances on universal life and annuity contracts (Note 1)			(499,374)	(431,743)
Net cash provided by (used in) financing activities			(447,402)	(226,137)
Effect of foreign exchange			(10)	374
Retained earnings:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity	2,669,327	2,576,241	2,669,327	2,576,241	2,627,389	2,382,152
Benefits and expenses:
Net earnings	29,634	96,527	41,938	194,089
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period	2,639,693	2,479,714	2,627,389	2,382,152
Net earnings (loss)	29,634	96,527	41,938	194,089
Total stockholders’ equity, end of period	2,669,327	2,576,241	2,669,327	2,576,241
Cash flows from operating activities:
Net earnings	29,634	96,527	41,938	194,089
Total Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity	(432,879)	(354,818)	(432,879)	(354,818)	(478,219)	297,649
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		(62,018)	(478,219)	297,649
Change during period		(292,800)		(652,467)
Total stockholders’ equity, end of period	(432,879)	(354,818)	(432,879)	(354,818)
Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity	(599,915)	(444,209)	(599,915)	(444,209)	(653,431)	367,109
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period	(528,283)	(74,039)	(653,431)	367,109
Other comprehensive income (loss), net of income tax	(71,632)	(370,170)	53,516	(811,318)
Total stockholders’ equity, end of period	(599,915)	(444,209)	(599,915)	(444,209)
Change in LFPB due to discount rate changes:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity	163,331	96,167	163,331	96,167	170,701	(60,121)
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period	148,987	19,911	170,701	(60,121)
Impact of discount rate changes during the period		76,256		156,288
Total stockholders’ equity, end of period	163,331	96,167	163,331	96,167
Foreign currency translation adjustments:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity	6,442	6,323	6,442	6,323	6,450	6,028
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period	6,420	6,343	6,450	6,028
Change in translation adjustments during period	22	(20)	(8)	295
Total stockholders’ equity, end of period	6,442	6,323	6,442	6,323
Class A (Note 4)
Benefits and expenses:
Net earnings	$ 28,796	$ 93,797	$ 40,752	$ 188,600
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 8.38	$ 27.30	$ 11.86	$ 54.89
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 8.38	$ 27.30	$ 11.86	$ 54.89
Condensed Consolidated Statement of Changes in Stockholders' Equity
Net earnings (loss)	$ 28,796	$ 93,797	$ 40,752	$ 188,600
Cash flows from operating activities:
Net earnings	28,796	93,797	40,752	188,600
Class B (Note 4)
Benefits and expenses:
Net earnings	$ 838	$ 2,730	$ 1,186	$ 5,489
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 4.19	$ 13.65	$ 5.93	$ 27.44
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 4.19	$ 13.65	$ 5.93	$ 27.44
Condensed Consolidated Statement of Changes in Stockholders' Equity
Net earnings (loss)	$ 838	$ 2,730	$ 1,186	$ 5,489
Cash flows from operating activities:
Net earnings	$ 838	2,730	1,186	5,489
As previously Reported
Assets:
Deferred policy acquisition costs					909,786
Deferred sales inducements					114,399
Value of business acquired					146,494
Market risk benefit assets					0
Deferred federal income tax asset					57,867
Amounts recoverable from reinsurer, net of allowance for credit losses					1,723,347
Other assets					110,339
Total assets					13,100,227
Future policyholder obligations:
Universal life and annuity contracts					8,498,684
Traditional life reserves					919,650
Liability for policyholder account balances					0
Additional liability for benefits in excess of account balance					0
Liability for future policy benefits					0
Market risk benefits liability					0
Other liabilities					166,557
Total liabilities					11,093,016
STOCKHOLDERS’ EQUITY:
Accumulated other comprehensive income (loss)					(416,397)
Retained earnings					2,381,856
Total stockholders’ equity		2,095,549		2,095,549	2,007,211	2,539,691
Total liabilities and stockholders' equity					13,100,227
Premiums and other revenues:
Universal life and annuity contract charges		32,692		65,343
Traditional life and SPIAWLC premiums		21,647		43,980
Total revenues		117,157		251,456
Benefits and expenses:
Life and other policy benefits		35,177		77,076
Market risk benefits expense		0		0
Deferred transaction costs		27,756		56,772
Universal life and annuity contract interest		(13,801)		(28,606)
Total benefits and expenses		79,453		168,145
Federal income taxes		6,939		16,362
Net earnings		30,765		66,949
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		2,297,981	2,007,211	2,539,691
Net earnings (loss)		30,765		66,949
Total stockholders’ equity, end of period		2,095,549		2,095,549
Cash flows from operating activities:
Net earnings		30,765		66,949
Universal life and annuity contract interest		(13,801)		(28,606)
(Increase) decrease in deferred policy acquisition and sales inducement costs, and value of business acquired				24,380
(Increase) decrease in reinsurance recoverable				87,357
(Increase) decrease in other assets (Note 1)				434
Increase (decrease) in liabilities for future policy benefits				43,768
Increase (decrease) in market risk benefits liability				0
Increase (decrease) in deferred Federal income tax				13,449
Increase (decrease) in other liabilities (Note 1)				(12,479)
Net cash provided by operating activities				139,289
Cash flows from financing activities:
Deposits to account balances for universal life and annuity contracts (Note 1)				210,438
Return of account balances on universal life and annuity contracts (Note 1)				(437,626)
Net cash provided by (used in) financing activities				(227,357)
Effect of foreign exchange				368
As previously Reported | Retained earnings:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		2,348,935		2,348,935	2,381,856	2,281,986
Benefits and expenses:
Net earnings		30,765		66,949
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		2,318,170	2,381,856	2,281,986
Net earnings (loss)		30,765		66,949
Total stockholders’ equity, end of period		2,348,935		2,348,935
Cash flows from operating activities:
Net earnings		30,765		66,949
As previously Reported | Total Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		(295,138)		(295,138)	(416,397)	215,953
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		(61,941)	(416,397)	215,953
Change during period		(233,197)		(511,091)
Total stockholders’ equity, end of period		(295,138)		(295,138)
As previously Reported | Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		(287,430)		(287,430)	(419,965)	226,220
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		(53,121)	(419,965)	226,220
Other comprehensive income (loss), net of income tax		(234,309)		(513,650)
Total stockholders’ equity, end of period		(287,430)		(287,430)
As previously Reported | Change in LFPB due to discount rate changes:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		0		0	0	0
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		0	0	0
Impact of discount rate changes during the period		0		0
Total stockholders’ equity, end of period		0		0
As previously Reported | Foreign currency translation adjustments:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		5,391		5,391	5,507	5,100
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		5,413	5,507	5,100
Change in translation adjustments during period		(22)		291
Total stockholders’ equity, end of period		$ 5,391		$ 5,391
As previously Reported | Class A (Note 4)
Basic earnings per share:
Basic earnings per share (in dollars per share)		$ 8.70		$ 18.93
Diluted earnings per share:
Diluted earnings per share (in dollars per share)		8.70		18.93
As previously Reported | Class B (Note 4)
Basic earnings per share:
Basic earnings per share (in dollars per share)		4.35		9.47
Diluted earnings per share:
Diluted earnings per share (in dollars per share)		$ 4.35		$ 9.47
Effect of Change
Assets:
Deferred policy acquisition costs					(245,904)
Deferred sales inducements					(29,096)
Value of business acquired					(7,999)
Market risk benefit assets					48,759
Deferred federal income tax asset					(48,835)
Amounts recoverable from reinsurer, net of allowance for credit losses					(34,559)
Other assets					352
Total assets					(317,282)
Future policyholder obligations:
Universal life and annuity contracts					(8,498,684)
Traditional life reserves					(919,650)
Liability for policyholder account balances					7,661,785
Additional liability for benefits in excess of account balance					148,708
Liability for future policy benefits					900,146
Market risk benefits liability					215,777
Other liabilities					(9,075)
Total liabilities					(500,993)
STOCKHOLDERS’ EQUITY:
Accumulated other comprehensive income (loss)					(61,822)
Retained earnings					245,533
Total stockholders’ equity		$ 167,626		$ 167,626	183,711	181,862
Total liabilities and stockholders' equity					(317,282)
Premiums and other revenues:
Universal life and annuity contract charges		129		275
Traditional life and SPIAWLC premiums		994		4,802
Total revenues		1,123		5,077
Benefits and expenses:
Life and other policy benefits		(8,976)		(17,363)
Market risk benefits expense		(55,492)		(116,498)
Deferred transaction costs		(5,256)		(10,836)
Universal life and annuity contract interest		(12,397)		(11,163)
Total benefits and expenses		(82,120)		(155,860)
Federal income taxes		17,481		33,797
Net earnings		65,762		127,140
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		161,467	183,711	181,862
Net earnings (loss)		65,762		127,140
Total stockholders’ equity, end of period		167,626		167,626
Cash flows from operating activities:
Net earnings		65,762		127,140
Universal life and annuity contract interest		(12,397)		(11,163)
(Increase) decrease in deferred policy acquisition and sales inducement costs, and value of business acquired				(12,528)
(Increase) decrease in reinsurance recoverable				44,016
(Increase) decrease in other assets (Note 1)				9
Increase (decrease) in liabilities for future policy benefits				(59,422)
Increase (decrease) in market risk benefits liability				(123,075)
Increase (decrease) in deferred Federal income tax				33,796
Increase (decrease) in other liabilities (Note 1)				1
Net cash provided by operating activities				(1,226)
Cash flows from financing activities:
Deposits to account balances for universal life and annuity contracts (Note 1)				(4,663)
Return of account balances on universal life and annuity contracts (Note 1)				5,883
Net cash provided by (used in) financing activities				1,220
Effect of foreign exchange				6
Effect of Change | Retained earnings:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		227,306		227,306	245,533	100,166
Benefits and expenses:
Net earnings		65,762		127,140
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		161,544	245,533	100,166
Net earnings (loss)		65,762		127,140
Total stockholders’ equity, end of period		227,306		227,306
Cash flows from operating activities:
Net earnings		65,762		127,140
Effect of Change | Total Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		(59,680)		(59,680)	(61,822)	81,696
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		(77)	(61,822)	81,696
Change during period		(59,603)		(141,376)
Total stockholders’ equity, end of period		(59,680)		(59,680)
Effect of Change | Accumulated Other Comprehensive Income (Loss):
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		(156,779)		(156,779)	(233,466)	140,889
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		(20,918)	(233,466)	140,889
Other comprehensive income (loss), net of income tax		(135,861)		(297,668)
Total stockholders’ equity, end of period		(156,779)		(156,779)
Effect of Change | Change in LFPB due to discount rate changes:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		96,167		96,167	170,701	(60,121)
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		19,911	170,701	(60,121)
Impact of discount rate changes during the period		76,256		156,288
Total stockholders’ equity, end of period		96,167		96,167
Effect of Change | Foreign currency translation adjustments:
STOCKHOLDERS’ EQUITY:
Total stockholders’ equity		932		932	$ 943	$ 928
Condensed Consolidated Statement of Changes in Stockholders' Equity
Total stockholders’ equity, beginning of period		930	$ 943	928
Change in translation adjustments during period		2		4
Total stockholders’ equity, end of period		$ 932		$ 932
Effect of Change | Class A (Note 4)
Basic earnings per share:
Basic earnings per share (in dollars per share)		$ 18.60		$ 35.96
Diluted earnings per share:
Diluted earnings per share (in dollars per share)		18.60		35.96
Effect of Change | Class B (Note 4)
Basic earnings per share:
Basic earnings per share (in dollars per share)		9.30		17.97
Diluted earnings per share:
Diluted earnings per share (in dollars per share)		$ 9.30		$ 17.97