Schedule II - Condensed Financial Information of Registrant (Balance Sheets (Parent Company)) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Cash and cash equivalents	$ 1,449,346	$ 1,568,843
Fixed maturity securities available for sale at fair value (cost $285,900 and $805,211 at December 31, 2022 and 2021, respectively)	17,587,349	16,602,673
Loans receivable (net of allowance for expected credit losses of $559 and $647 at December 31, 2022 and 2021, respectively)	193,002	115,172
Current federal income taxes	39,123	23,570
Deferred federal and foreign income taxes	340,647	57,425
Property, furniture and equipment at cost, less accumulated depreciation	423,232	419,883
Other assets	736,022	753,231
Total assets	33,861,099	32,086,414
Liabilities:
Other liabilities	1,377,740	1,305,245
Current federal income taxes	34,350	21,068
Deferred federal income taxes	11,646	17,470
Subordinated debentures	1,008,371	1,007,652
Total liabilities	27,092,938	25,418,684
Stockholders' equity:
Preferred stock	0	0
Common stock	105,803	105,803
Additional paid-in capital	997,534	981,104
Retained earnings (including accumulated undistributed net income of subsidiaries of $7,975,360 and $6,463,882 at December 31, 2022 and 2021, respectively)	10,161,005	9,015,135
Accumulated other comprehensive loss	(1,264,581)	(281,955)
Treasury stock, at cost	(3,251,429)	(3,167,076)
Total common stockholders’ equity	6,748,332	6,653,011
Total liabilities and equity	33,861,099	32,086,414
Fixed maturity securities available for sale at cost	18,664,073	16,396,936
Financing receivable, allowance for credit loss	1,791	1,718	$ 5,437
Parent Company
Assets:
Cash and cash equivalents	103,522	684,037
Fixed maturity securities available for sale at fair value (cost $285,900 and $805,211 at December 31, 2022 and 2021, respectively)	275,511	806,074
Loans receivable (net of allowance for expected credit losses of $559 and $647 at December 31, 2022 and 2021, respectively)	109,793	93,397
Equity securities, at fair value (cost $3,430 in both 2022 and 2021)	3,430	3,430
Investment in subsidiaries	8,888,455	8,516,916
Current federal income taxes	34,452	23,424
Deferred federal and foreign income taxes	304,191	11,796
Property, furniture and equipment at cost, less accumulated depreciation	11,356	11,916
Other assets	39,741	43,793
Total assets	9,770,451	10,194,783
Liabilities:
Due to subsidiaries	53,029	138,376
Other liabilities	139,150	146,892
Subordinated debentures	1,008,371	1,007,652
Senior notes	1,821,569	2,248,852
Total liabilities	3,022,119	3,541,772
Stockholders' equity:
Preferred stock	0	0
Common stock	105,803	105,803
Additional paid-in capital	997,534	981,104
Retained earnings (including accumulated undistributed net income of subsidiaries of $7,975,360 and $6,463,882 at December 31, 2022 and 2021, respectively)	10,161,005	9,015,135
Accumulated other comprehensive loss	(1,264,581)	(281,955)
Treasury stock, at cost	(3,251,429)	(3,167,076)
Total common stockholders’ equity	6,748,332	6,653,011
Total liabilities and equity	9,770,451	10,194,783
Fixed maturity securities available for sale at cost	285,900	805,211
Financing receivable, allowance for credit loss	559	647
Equity securities available for sale at cost	3,430	3,430
Accumulated undistributed net income of subsidiaries	$ 7,975,360	$ 6,463,882