Schedule II Financial Information of Registrant - Parent Company Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Net Investment Income	$ 38,115	$ 36,255	$ 38,723	$ 40,944	$ 41,432	$ 42,756	$ 43,761	$ 43,847	$ 154,037	$ 171,796	$ 152,475
Net gains (losses) on investments and other financial instruments	17,376	17,652	47,276	(22,027)	4,257	13,009	12,540	21,913	60,277	51,719	(42,476)
Other income									3,597	3,495	4,028
Total revenues									1,438,617	1,526,955	1,273,006
Expenses:
Loss on extinguishment of debt					0	(5,940)	(16,798)	0	0	(22,738)	0
Interest expense									71,150	56,310	61,490
Total expenses (Note B)									959,176	677,962	588,820
Pretax income									479,441	848,993	684,186
Income tax benefit									85,815	176,684	78,175
Net income	148,013	135,103	(29,951)	140,461	161,184	173,438	166,730	170,957	393,626	672,309	606,011
Other comprehensive income (loss), net of tax									153,237	171,408	(86,953)
Comprehensive income									546,863	843,717	519,058
Other operating expenses	$ 81,641	$ 69,377	$ 60,582	$ 69,110	$ 80,894	$ 76,384	$ 70,046	$ 78,805	280,710	306,129	280,818
Parent Company
Revenues:
Net Investment Income									19,459	19,751	21,294
Net gains (losses) on investments and other financial instruments									5,682	12,863	(470)
Other income									101	218	0
Total revenues									25,242	32,832	20,824
Expenses:
Loss on extinguishment of debt									0	22,738	0
Interest expense									0	0	17,805
Total expenses (Note B)									2,619	22,738	17,805
Pretax income									22,623	10,094	3,019
Income tax benefit									(3,165)	(19,997)	(3,319)
Equity in net income of affiliates									367,838	642,218	599,673
Net income									393,626	672,309	606,011
Other comprehensive income (loss), net of tax									153,237	171,408	(86,953)
Comprehensive income									546,863	843,717	519,058
Other operating expenses									$ 2,619	$ 0	$ 0