Schedule II - Condensed Financial Information of Registrant (Statements of Income (Parent Company)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Income Statements, Captions [Line Items]
Net investment gains	$ 90,632	$ 103,000	$ 120,703
Other income	4,177	2,596	3,370
Total revenues	9,455,466	8,098,925	7,902,196
Operating costs and expense	8,172,561	7,394,123	7,049,276
Income before income taxes	1,282,905	704,802	852,920
Federal income taxes:
Net federal income tax expense	(251,890)	(171,817)	(168,935)
Net income to common stockholders	1,022,490	530,670	681,944
Dividends from subsidiaries	520,251	617,424	416,027
Parent Company
Condensed Income Statements, Captions [Line Items]
Management fees and investment income including dividends from subsidiaries of $520,251, $617,424, and $416,027 for the years ended December 31, 2021, 2020 and 2019, respectively	548,512	654,485	470,773
Net investment gains	1,474	3,580	850
Other income	1,138	568	117
Total revenues	551,124	658,633	471,740
Operating costs and expense	214,995	166,892	204,812
Interest expense	144,837	145,417	148,282
Income before income taxes	191,292	346,324	118,646
Federal income taxes:
Federal income taxes provided by subsidiaries on a separate return basis	294,731	188,490	207,647
Federal income tax expense on a consolidated return basis	(226,900)	(139,679)	(141,190)
Net federal income tax expense	67,831	48,811	66,457
Income before undistributed equity in net income of subsidiaries	259,123	395,135	185,103
Equity in undistributed net income of subsidiaries	763,367	135,535	496,841
Net income to common stockholders	$ 1,022,490	$ 530,670	$ 681,944