Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Net income	$ 1,070,762	$ 970,755	$ 894,386
Adjustments to reconcile net income to cash provided from operations:
Increase (decrease) in future policy benefits	731,417	834,366	759,426
Increase (decrease) in other policy benefits	19,268	5,448	35,638
Deferral of policy acquisition costs	(913,544)	(850,169)	(828,943)
Amortization of deferred acquisition costs	410,001	379,700	348,824
Change in current and deferred income taxes	77,930	101,448	91,835
Realized (gains) losses	24,188	65,676	76,548
Other, net	(17,582)	(24,799)	44,480
Cash provided from (used for) operating activities	1,402,440	1,482,425	1,422,194
Investments sold or matured:
Fixed maturities available for sale—sold	1,207,237	602,556	390,392
Fixed maturities available for sale—matured or other redemptions	214,442	250,652	462,002
Mortgage loans	54,157	44,004	32,870
Other long-term investments	43,362	151,262	50,281
Total investments sold or matured	1,519,198	1,048,474	935,545
Acquisition of investments:
Fixed maturities—available for sale	(1,379,238)	(1,536,409)	(1,420,220)
Mortgage loans	(174,665)	(158,823)	(77,275)
Other long-term investments	(459,660)	(155,700)	(213,207)
Total investments acquired	(2,013,563)	(1,850,932)	(1,710,702)
Net (increase) decrease in policy loans	(42,649)	(42,154)	(25,232)
Net (increase) decrease in short-term investments	(3,295)	32,381	(44,976)
Additions to property and equipment	(71,045)	(49,553)	(27,929)
Other investing activities	96	0	0
Investments in low-income housing interests	(30,258)	(64,365)	(69,721)
Cash provided from (used for) investing activities	(641,516)	(926,149)	(943,015)
Cash provided from (used for) financing activities:
Issuance of common stock	51,786	114,080	106,592
Cash dividends paid to shareholders	(85,485)	(84,116)	(80,547)
Repayment of debt	0	(165,612)	(150,000)
Proceeds from issuance of debt	530,000	170,000	250,492
Payment for debt issuance costs	(7,253)	(757)	(5,272)
Net borrowing (repayment) of commercial paper	(13,878)	32,961	(46,289)
Proceeds from commercial paper with original maturities greater than 90 days	484,726	0	0
Repayment of commercial paper with original maturities greater than 90 days	(372,011)	0	0
Acquisition of treasury stock	(1,002,109)	(511,100)	(454,638)
Amounts paid to reinsurer	(413,779)	0	0
Net receipts (payments) from deposit-type products	112,168	(96,943)	(112,791)
Cash provided from (used for) financing activities	(715,835)	(541,487)	(492,453)
Effect of foreign exchange rate changes on cash	17,080	(4,192)	13,670
Net increase (decrease) in cash	62,169	10,597	396
Cash at beginning of year	103,156	92,559	92,163
Cash at end of year	$ 165,325	$ 103,156	$ 92,559