Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Statement of Cash Flows [Abstract]
Cash provided from (used for) operating activities	$ 769,302	$ 686,637
Cash provided from (used for) investing activities:
Fixed maturities available for sale—sold	52,020	34,997
Fixed maturities available for sale—matured or other redemptions	218,022	440,796
Other long-term investments	29,058	0
Total investments sold or matured	299,100	475,793
Acquisition of investments:
Fixed maturities—available for sale	(562,875)	(703,406)
Other long-term investments	(156,291)	(80,979)
Total investments acquired	(719,166)	(784,385)
Net (increase) decrease in policy loans	(4,049)	(10,403)
Net (increase) decrease in short-term investments	(493,366)	(1,806)
Additions to properties	(20,145)	(21,654)
Sale of other assets	18	15
Investments in low-income housing interests	(23,049)	(13,916)
Cash provided from (used for) investing activities	(960,657)	(356,356)
Cash provided from (used for) financing activities:
Issuance of common stock	17,525	39,598
Cash dividends paid to shareholders	(38,541)	(36,652)
Repayment of debt	(4,375)	(3,125)
Proceeds from issuance of debt	300,000	0
Payment for debt issuance costs	(891)	0
Net borrowing (repayment) of commercial paper	159,920	(51,645)
Acquisition of treasury stock	(166,729)	(230,097)
Net receipts (payments) from deposit-type products	(44,873)	(74,217)
Cash provided from (used for) financing activities	222,036	(356,138)
Effect of foreign exchange rate changes on cash	7,417	(5,850)
Net increase (decrease) in cash	38,098	(31,707)
Cash at beginning of year	75,933	121,026
Cash at end of period	$ 114,031	$ 89,319