Reinsurance (Reinsurance amounts included in the Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Premiums:
Direct	$ 462,271	$ 441,955
Assumed	54	60
Ceded	(448,331)	(434,100)
Net premiums	13,994	7,915
Policy charges and fee income:
Direct	853,195	846,247
Assumed	126,959	121,709
Ceded	(840,965)	(838,801)
Net policy charges and fee income	139,189	129,155
Net investment income:
Direct	94,558	79,149
Assumed	396	373
Ceded	(1,704)	(1,607)
Net investment income	93,250	77,915
Asset administration fees:
Direct	83,868	87,033
Assumed	0	0
Ceded	(80,211)	(83,560)
Net asset administration fees	3,657	3,473
Other income:
Direct	19,798	17,253
Assumed	(200)	(90)
Ceded	(23)	(52)
Amortization of reinsurance income	1,382	2,185
Net other income	20,957	19,296
Realized investment gains (losses), net:
Direct	(635,511)	1,474,762
Assumed	0	0
Ceded	586,876	(1,523,804)
Realized investment gains (losses), net	(48,635)	(49,042)
Policyholders’ benefits (including change in reserves):
Direct	646,311	651,672
Assumed	211,750	112,802
Ceded	(818,583)	(712,738)
Net policyholders’ benefits (including change in reserves)	39,478	51,736
Interest credited to policyholders’ account balances:
Direct	94,691	124,734
Assumed	30,657	36,517
Ceded	(81,151)	(120,453)
Net interest credited to policyholders’ account balances	44,197	40,798
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(344,015)	(434,371)
Unaffiliated activity
Premiums:
Assumed	100	100
Ceded	(100)	0
Policy charges and fee income:
Ceded	(5,000)	(2,000)
Other income:
Assumed	(200)	(100)
Realized investment gains (losses), net:
Ceded	14,000	(38,000)
Policyholders’ benefits (including change in reserves):
Assumed	(200)	(100)
Ceded	$ (2,000)	$ (2,000)