Schedule II Financial Information of Registrant Parent Company Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Net investment income (Note 6)	$ 41,432	$ 42,756	$ 43,761	$ 43,847	$ 42,051	$ 38,995	$ 37,473	$ 33,956	$ 171,796	$ 152,475	$ 127,248
Net gains (losses) on investments and other financial instruments	4,257	13,009	12,540	21,913	(11,705)	(4,480)	(7,404)	(18,887)	51,719	(42,476)	3,621
Other income									3,495	4,028	2,886
Total revenues									1,526,955	1,273,006	1,221,631
Expenses:
Loss on extinguishment of debt									(22,738)	0	(51,469)
Interest expense									56,310	61,490	62,761
Total expenses (Note B)									677,962	588,820	874,894
Pretax income (loss)									848,993	684,186	346,737
Income tax benefit									176,684	78,175	225,649
Net income	$ 161,184	$ 173,438	$ 166,730	$ 170,957	$ 139,779	$ 142,797	$ 208,949	$ 114,486	672,309	606,011	121,088
Other comprehensive income (loss), net of tax									171,408	(86,953)	35,480
Comprehensive income									843,717	519,058	156,568
Parent Company
Revenues:
Net investment income (Note 6)									19,751	21,294	22,528
Net gains (losses) on investments and other financial instruments									12,863	(470)	(328)
Other income									218	0	80
Total revenues									32,832	20,824	22,280
Expenses:
Loss on extinguishment of debt									22,738	0	51,469
Interest expense									0	17,805	18,033
Total expenses (Note B)									22,738	17,805	69,502
Pretax income (loss)									10,094	3,019	(47,222)
Income tax benefit									(19,997)	(3,319)	(141,437)
Equity in net income of affiliates									642,218	599,673	26,873
Net income									672,309	606,011	121,088
Other comprehensive income (loss), net of tax									171,408	(86,953)	35,480
Comprehensive income									$ 843,717	$ 519,058	$ 156,568