Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Statement of Cash Flows [Abstract]
Cash provided from (used for) operating activities	$ 1,078,616	$ 1,030,175
Cash provided from (used for) investing activities:
Fixed maturities available for sale—sold	52,681	62,151
Fixed maturities available for sale—matured or other redemptions	333,631	604,701
Other long-term investments	35,547	0
Total investments sold or matured	421,859	666,852
Acquisition of investments:
Fixed maturities—available for sale	(905,371)	(1,056,822)
Other long-term investments	(213,075)	(107,660)
Total investments acquired	(1,118,446)	(1,164,482)
Net (increase) decrease in policy loans	(5,719)	(18,826)
Net (increase) decrease in short-term investments	(225,594)	(5,270)
Additions to properties	(28,790)	(30,049)
Other investing activities	(7,099)	32
Investments in low-income housing interests	(28,669)	(16,824)
Cash provided from (used for) investing activities	(992,458)	(568,567)
Cash provided from (used for) financing activities:
Issuance of common stock	27,337	57,573
Cash dividends paid to shareholders	(58,503)	(55,493)
Repayment of debt	(386,875)	(5,000)
Proceeds from issuance of debt	700,000	0
Payment for debt issuance costs	(5,844)	0
Net borrowing (repayment) of commercial paper	(9,605)	(76,409)
Acquisition of treasury stock	(296,648)	(334,469)
Net receipts (payments) from deposit-type products	(56,858)	(95,626)
Cash provided from (used for) financing activities	(86,996)	(509,424)
Effect of foreign exchange rate changes on cash	5,006	(6,535)
Net increase (decrease) in cash	4,168	(54,351)
Cash at beginning of year	75,933	121,026
Cash at end of period	$ 80,101	$ 66,675