Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Cash Flows [Abstract]
Net income	$ 739,704	$ 744,959	$ 731,773
Adjustments to reconcile net income to cash provided from operations:
Increase (decrease) in future policy benefits	828,028	854,770	798,936
Increase (decrease) in other policy benefits	36,784	18,144	33,810
Deferral of policy acquisition costs	(960,583)	(906,247)	(822,985)
Amortization of deferred policy acquisition costs	624,407	603,838	575,770
Change in current and deferred income taxes	50,718	71,919	88,157
Realized (gains) losses	76,548	(59,319)	4,371
Other, net	26,588	109,616	66,602
Cash provided from (used for) operating activities	1,422,194	1,437,680	1,476,434
Investments sold or matured:
Fixed maturities available for sale—sold	390,392	116,656	52,681
Fixed maturities available for sale—matured or other redemptions	462,002	310,991	416,321
Other long-term investments	83,151	36,346	42,990
Total investments sold or matured	935,545	463,993	511,992
Acquisition of investments:
Fixed maturities—available for sale	(1,420,220)	(1,004,384)	(1,262,434)
Other long-term investments	(290,482)	(258,296)	(266,230)
Total investments acquired	(1,710,702)	(1,262,680)	(1,528,664)
Net (increase) decrease in policy loans	(25,232)	(5,255)	(8,887)
Net (increase) decrease in short-term investments	(44,976)	38,637	(69,497)
Additions to property and equipment	(27,929)	(38,244)	(41,756)
Other investing activities	0	(56,700)	(7,051)
Investments in low-income housing interests	(69,721)	(53,121)	(37,867)
Cash provided from (used for) investing activities	(943,015)	(913,370)	(1,181,730)
Cash provided from (used for) financing activities:
Issuance of common stock	106,592	69,826	48,093
Cash dividends paid to shareholders	(80,547)	(80,043)	(78,192)
Repayment of debt	(150,000)	(300,000)	(386,875)
Proceeds from issuance of debt	250,492	325,000	700,000
Payment for debt issuance costs	(5,272)	(7,687)	(5,844)
Net borrowing (repayment) of commercial paper	(46,289)	74,974	(34,445)
Acquisition of treasury stock	(454,638)	(541,435)	(443,866)
Net receipts (payments) from deposit-type products	(112,791)	(64,238)	(72,928)
Cash provided from (used for) financing activities	(492,453)	(523,603)	(274,057)
Effect of foreign exchange rate changes on cash	13,670	(3,391)	(1,733)
Net increase (decrease) in cash	396	(2,684)	18,914
Cash at beginning of year	92,163	94,847	75,933
Cash at end of year	$ 92,559	$ 92,163	$ 94,847