Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Cash provided from (used for) operating activities	$ 343,554	$ 423,285
Cash provided from (used for) investing activities:
Fixed maturities available for sale—sold	50,360	34,997
Fixed maturities available for sale—matured or other redemptions	167,387	188,253
Other long-term investments	231	0
Total investments sold or matured	217,978	223,250
Acquisition of investments:
Fixed maturities—available for sale	(211,754)	(421,111)
Other long-term investments	(49,896)	(22,971)
Total investments acquired	(261,650)	(444,082)
Net (increase) decrease in policy loans	(3,641)	(5,390)
Net (increase) decrease in short-term investments	(234,316)	(62,471)
Additions to properties	(9,316)	(7,015)
Sale of other assets	13	0
Investments in low-income housing interests	(20,743)	(10,054)
Cash provided from (used for) investing activities	(311,675)	(305,762)
Cash provided from (used for) financing activities:
Issuance of common stock	16,808	11,592
Cash dividends paid to shareholders	(18,588)	(17,696)
Repayment of debt	(1,875)	(1,250)
Net borrowing (repayment) of commercial paper	158,764	(14,095)
Acquisition of treasury stock	(166,729)	(110,896)
Net receipts (payments) from deposit-type products	(19,651)	(37,136)
Cash provided from (used for) financing activities	(31,271)	(169,481)
Effect of foreign exchange rate changes on cash	13,829	(1,726)
Net increase (decrease) in cash	14,437	(53,684)
Cash at beginning of year	75,933	121,026
Cash at end of period	$ 90,370	$ 67,342