Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Cash Flows [Abstract]
Net income	$ 1,161,238	$ 1,070,762	$ 970,755
Adjustments to reconcile net income to cash provided from operations:
Increase (decrease) in future policy benefits	582,136	731,417	834,366
Increase (decrease) in other policy benefits	21,124	19,268	5,448
Deferral of policy acquisition costs	(941,922)	(913,544)	(850,169)
Amortization of deferred acquisition costs	447,760	410,001	379,700
Change in current and deferred income taxes	98,887	77,930	101,448
Realized (gains) losses	27,788	24,188	65,676
Other, net	(620)	(17,582)	(24,799)
Cash provided from (used for) operating activities	1,396,391	1,402,440	1,482,425
Investments sold or matured:
Fixed maturities available for sale—sold	623,792	1,207,237	602,556
Fixed maturities available for sale—matured or other redemptions	313,676	214,442	250,652
Mortgage loans	65,724	54,157	44,004
Other long-term investments	128,281	43,362	151,262
Total investments sold or matured	1,131,473	1,519,198	1,048,474
Acquisition of investments:
Fixed maturities—available for sale	(921,339)	(1,379,238)	(1,536,409)
Mortgage loans	(139,817)	(174,665)	(158,823)
Other long-term investments	(247,052)	(459,660)	(155,700)
Total investments acquired	(1,308,208)	(2,013,563)	(1,850,932)
Net (increase) decrease in policy loans	(41,706)	(42,649)	(42,154)
Net (increase) decrease in short-term investments	(229,676)	(3,295)	32,381
Additions to property and equipment	(142,484)	(71,045)	(49,553)
Other investing activities	0	96	0
Investments in low-income housing interests	(53,017)	(30,258)	(64,365)
Cash provided from (used for) investing activities	(643,618)	(641,516)	(926,149)
Cash provided from (used for) financing activities:
Issuance of common stock	164,448	51,786	114,080
Cash dividends paid to shareholders	(86,067)	(85,485)	(84,116)
Repayment of debt	0	0	(165,612)
Proceeds from issuance of debt	0	530,000	170,000
Payment for debt issuance costs	(6,399)	(7,253)	(757)
Net borrowing (repayment) of commercial paper	102,638	(13,878)	32,961
Proceeds from commercial paper with original maturities greater than 90 days	487,610	484,726	0
Repayment of commercial paper with original maturities greater than 90 days	(700,993)	(372,011)	0
Acquisition of treasury stock	(880,983)	(1,002,109)	(511,100)
Amounts paid to reinsurer	0	(413,779)	0
Net receipts (payments) from deposit-type products	151,694	112,168	(96,943)
Cash provided from (used for) financing activities	(768,052)	(715,835)	(541,487)
Effect of foreign exchange rate changes on cash	(5,342)	17,080	(4,192)
Net increase (decrease) in cash	(20,621)	62,169	10,597
Cash at beginning of year	165,325	103,156	92,559
Cash at end of year	$ 144,704	$ 165,325	$ 103,156