Reinsurance (Reinsurance amounts included in the Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Premiums:
Direct	$ 475,486	$ 462,271
Assumed	48	54
Ceded	(460,663)	(448,331)
Net premiums	14,871	13,994
Policy charges and fee income:
Direct	901,442	853,195
Assumed	132,504	126,959
Ceded	(894,027)	(840,965)
Net policy charges and fee income	139,919	139,189
Net investment income:
Direct	81,092	94,558
Assumed	400	396
Ceded	(1,911)	(1,704)
Net investment income	79,581	93,250
Asset administration fees:
Direct	89,329	83,868
Assumed	0	0
Ceded	(84,941)	(80,211)
Net asset administration fees	4,388	3,657
Other income:
Direct	8,606	19,798
Assumed	(437)	(200)
Ceded	(515)	(23)
Amortization of reinsurance income	1,182	1,382
Net other income	8,836	20,957
Realized investment gains (losses), net:
Direct	(11,309,174)	(635,511)
Assumed	0	0
Ceded	11,399,069	586,876
Realized investment gains (losses), net	89,895	(48,635)
Policyholders’ benefits (including change in reserves):
Direct	1,067,098	646,311
Assumed	361,455	211,750
Ceded	(1,342,630)	(818,583)
Net policyholders’ benefits (including change in reserves)	85,923	39,478
Interest credited to policyholders’ account balances:
Direct	179,295	94,691
Assumed	34,236	30,657
Ceded	(158,485)	(81,151)
Net interest credited to policyholders’ account balances	55,046	44,197
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(742,911)	(344,015)
Unaffiliated activity
Premiums:
Assumed	0	100
Ceded	(2,500)	(100)
Policy charges and fee income:
Ceded	(10,000)	(5,000)
Other income:
Assumed	(400)	(200)
Realized investment gains (losses), net:
Ceded	256,100	14,400
Policyholders’ benefits (including change in reserves):
Assumed	100	(200)
Ceded	$ (5,000)	$ (1,800)