Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Net income	$ 970,755	$ 894,386	$ 1,031,114
Adjustments to reconcile net income to cash provided from operations:
Increase (decrease) in future policy benefits	834,366	759,426	645,897
Increase (decrease) in other policy benefits	5,448	35,638	31,533
Deferral of policy acquisition costs	(850,169)	(828,943)	(782,488)
Amortization of deferred acquisition costs	379,700	348,824	317,616
Change in current and deferred income taxes	101,448	91,835	147,990
Realized (gains) losses	65,676	76,548	(59,319)
Other, net	(24,799)	44,480	105,337
Cash provided from (used for) operating activities	1,482,425	1,422,194	1,437,680
Investments sold or matured:
Fixed maturities available for sale—sold	602,556	390,392	116,656
Fixed maturities available for sale—matured or other redemptions	250,652	462,002	310,991
Mortgage loans	44,004	32,870	31,423
Other long-term investments	151,262	50,281	4,923
Total investments sold or matured	1,048,474	935,545	463,993
Acquisition of investments:
Fixed maturities—available for sale	(1,536,409)	(1,420,220)	(1,004,384)
Mortgage loans	(158,823)	(77,275)	(10,421)
Other long-term investments	(155,700)	(213,207)	(247,875)
Total investments acquired	(1,850,932)	(1,710,702)	(1,262,680)
Net (increase) decrease in policy loans	(42,154)	(25,232)	(5,255)
Net (increase) decrease in short-term investments	32,381	(44,976)	38,637
Additions to property and equipment	(49,553)	(27,929)	(38,244)
Other investing activities	0	0	(56,700)
Investments in low-income housing interests	(64,365)	(69,721)	(53,121)
Cash provided from (used for) investing activities	(926,149)	(943,015)	(913,370)
Cash provided from (used for) financing activities:
Issuance of common stock	114,080	106,592	69,826
Cash dividends paid to shareholders	(84,116)	(80,547)	(80,043)
Repayment of debt	(165,612)	(150,000)	(300,000)
Proceeds from issuance of debt	170,000	250,492	325,000
Payment for debt issuance costs	(757)	(5,272)	(7,687)
Net borrowing (repayment) of commercial paper	32,961	(46,289)	74,974
Acquisition of treasury stock	(511,100)	(454,638)	(541,435)
Net receipts (payments) from deposit-type products	(96,943)	(112,791)	(64,238)
Cash provided from (used for) financing activities	(541,487)	(492,453)	(523,603)
Effect of foreign exchange rate changes on cash	(4,192)	13,670	(3,391)
Net increase (decrease) in cash	10,597	396	(2,684)
Cash at beginning of year	92,559	92,163	94,847
Cash at end of year	$ 103,156	$ 92,559	$ 92,163