Reinsurance (Reinsurance amounts included in the Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Premiums:
Direct	$ 484,577	$ 476,986	$ 960,063	$ 939,257
Assumed	47	52	95	106
Ceded	(462,080)	(464,621)	(922,743)	(912,952)
Net premiums	22,544	12,417	37,415	26,411
Policy charges and fee income:
Direct	816,817	1,106,725	1,718,259	1,959,920
Assumed	131,579	128,748	264,083	255,707
Ceded	(787,311)	(1,086,802)	(1,681,338)	(1,927,767)
Net policy charges and fee income	161,085	148,671	301,004	287,860
Net investment income:
Direct	84,946	106,949	166,038	201,507
Assumed	394	407	794	803
Ceded	(1,878)	(1,794)	(3,789)	(3,498)
Net investment income	83,462	105,562	163,043	198,812
Asset administration fees:
Direct	84,330	87,951	173,659	171,819
Assumed	0	0	0	0
Ceded	(80,028)	(83,990)	(164,969)	(164,201)
Net asset administration fees	4,302	3,961	8,690	7,618
Other income:
Direct	12,682	20,030	21,288	39,828
Assumed	408	(1,271)	(29)	(1,471)
Ceded	640	(39)	125	(62)
Amortization of reinsurance income	1,162	(3,722)	2,344	(2,340)
Net other income	14,892	14,998	23,728	35,955
Realized investment gains (losses), net:
Direct	1,408,425	(1,783,941)	(9,900,749)	(2,419,452)
Assumed	0	0	0	0
Ceded	(1,488,656)	1,731,691	9,910,413	2,318,567
Realized investment gains (losses), net	(80,231)	(52,250)	9,664	(100,885)
Policyholders’ benefits (including change in reserves):
Direct	744,620	1,150,985	1,811,718	1,797,296
Assumed	208,315	282,961	569,770	494,711
Ceded	(866,682)	(1,387,655)	(2,209,312)	(2,206,238)
Net policyholders’ benefits (including change in reserves)	86,253	46,291	172,176	85,769
Interest credited to policyholders’ account balances:
Direct	92,457	118,420	271,752	213,111
Assumed	34,020	34,512	68,256	65,169
Ceded	(60,060)	(102,222)	(218,545)	(183,373)
Net interest credited to policyholders’ account balances	66,417	50,710	121,463	94,907
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(139,336)	(573,978)	(882,247)	(917,993)
Unaffiliated activity
Premiums:
Assumed	100	0	100	100
Ceded	(2,600)	(100)	(5,100)	(200)
Policy charges and fee income:
Ceded	(11,000)	(7,000)	(21,000)	(12,000)
Other income:
Assumed	(400)	(1,000)	0	(2,000)
Realized investment gains (losses), net:
Ceded	(29,000)	42,000	227,000	56,000
Policyholders’ benefits (including change in reserves):
Assumed	500	0	600	(200)
Ceded	$ (19,000)	$ (2,000)	$ (24,000)	$ (4,000)