Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement of Cash Flows [Abstract]
Cash provided from operations	$ 454,121	$ 419,383
Long-term investments sold or matured:
Fixed maturities available for sale—sold	14,287	28,194
Fixed maturities available for sale—matured, called, and repaid	213,989	107,394
Equity securities	0	700
Other long-term investments	431	23
Total long-term investments sold or matured	228,707	136,311
Long-term investments acquired:
Fixed maturities	(541,875)	(325,574)
Other long-term investments	(1,886)	0
Total long-term investments acquired	(543,761)	(325,574)
Net increase in policy loans	(7,844)	(8,937)
Net (increase) decrease in short-term investments	(12,813)	28,329
Net change in payable or receivable for securities	4,980	0
Disposition of properties	0	19
Additions to properties	(13,949)	(10,006)
Investment in low-income housing interests	(11,954)	(22,030)
Cash used for investment activities	(356,634)	(201,888)
Cash provided from (used for) financing activities:
Proceeds from exercise of stock options	21,507	35,015
Net borrowings (repayments) of commercial paper	148,970	45,874
Excess tax benefit from stock option exercises	10,989	11,098
Acquisition of treasury stock	(211,567)	(238,313)
Cash dividends paid to shareholders	(33,306)	(31,980)
Net receipts (withdrawals) from deposit-type products	(42,815)	(33,104)
Cash provided by (used for) financing activities	(106,222)	(211,410)
Effect of foreign exchange rate changes on cash	5,565	2,775
Net (decrease) increase in cash	(3,170)	8,860
Cash at beginning of year	66,019	36,943
Cash at end of period	$ 62,849	$ 45,803