Schedule II - Condensed Financial Information of Registrant (Balance Sheets (Parent Company)) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets:
Cash and cash equivalents	$ 1,568,843	$ 2,372,366
Fixed maturity securities available for sale at fair value (cost $805,211 and $792,752 at December 31, 2021 and 2020, respectively)	16,602,673	14,159,369
Loans receivable (net of allowance for expected credit losses of $647 and $28 at December 31, 2021 and 2020, respectively)	115,172	84,913
Current federal income taxes	23,570	5,893
Deferred federal and foreign income taxes	57,425	29,055
Property, furniture and equipment at cost, less accumulated depreciation	419,883	405,930
Other assets	753,231	700,215
Total assets	32,086,414	28,606,913
Liabilities:
Other liabilities	1,305,245	1,178,546
Current federal income taxes	21,068	41,282
Deferred federal income taxes	17,470	42,161
Subordinated debentures		1,102,309
Total liabilities	25,418,684	22,281,116
Stockholders' equity:
Preferred stock	0	0
Common stock	70,535	70,535
Additional paid-in capital	1,016,372	1,012,483
Retained earnings (including accumulated undistributed net income of subsidiaries of $6,463,882 and $5,700,515 at December 31, 2021 and 2020, respectively)	9,015,135	8,348,381
Accumulated other comprehensive loss	(281,955)	(62,172)
Treasury stock, at cost	(3,167,076)	(3,058,425)
Total common stockholders’ equity	6,653,011	6,310,802
Total liabilities and equity	32,086,414	28,606,913
Fixed maturity securities available for sale at cost	16,396,936	13,682,286
Financing receivable, allowance for credit loss	1,718	5,437	$ 2,146
Parent Company
Assets:
Cash and cash equivalents	684,037	296,960
Fixed maturity securities available for sale at fair value (cost $805,211 and $792,752 at December 31, 2021 and 2020, respectively)	806,074	800,263
Loans receivable (net of allowance for expected credit losses of $647 and $28 at December 31, 2021 and 2020, respectively)	93,397	75,789
Equity securities, at fair value (cost $3,430 in 2021 and 2020 respectively)	3,430	3,430
Investment in subsidiaries	8,516,916	7,957,501
Current federal income taxes	23,424	0
Deferred federal and foreign income taxes	11,796	0
Property, furniture and equipment at cost, less accumulated depreciation	11,916	11,412
Other assets	43,793	11,231
Total assets	10,194,783	9,156,586
Liabilities:
Due to subsidiaries	138,376	77,860
Other liabilities	146,892	106,064
Current federal income taxes	0	15,662
Deferred federal income taxes	0	31,851
Subordinated debentures	1,007,652	1,102,309
Senior notes	2,248,852	1,512,038
Total liabilities	3,541,772	2,845,784
Stockholders' equity:
Preferred stock	0	0
Common stock	70,535	70,535
Additional paid-in capital	1,016,372	1,012,483
Retained earnings (including accumulated undistributed net income of subsidiaries of $6,463,882 and $5,700,515 at December 31, 2021 and 2020, respectively)	9,015,135	8,348,381
Accumulated other comprehensive loss	(281,955)	(62,172)
Treasury stock, at cost	(3,167,076)	(3,058,425)
Total common stockholders’ equity	6,653,011	6,310,802
Total liabilities and equity	10,194,783	9,156,586
Fixed maturity securities available for sale at cost	805,211	792,752
Financing receivable, allowance for credit loss	647	28
Equity securities available for sale at cost	3,430	3,430
Accumulated undistributed net income of subsidiaries	$ 6,463,882	$ 5,700,515