Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 79,165	$ 65,715
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Change in future policy benefits and other policy liabilities	65,733	69,052
Deferral of policy acquisition costs	(105,080)	(111,422)
Amortization of deferred policy acquisition costs	64,628	60,165
Change in income taxes	6,180	6,444
Realized investment (gains) losses, including other-than-temporary impairments	(2,847)	1,656
Accretion and amortization of investments	(120)	(126)
Depreciation and amortization	4,156	3,044
Change in reinsurance recoverables	(54,860)	(66,974)
Change in agent balances, due premiums and other receivables	(7,910)	2,440
Trading securities sold, matured, or called (acquired), net	(12,918)	(24,025)
Share-based compensation	10,896	11,502
Change in other operating assets and liabilities, net	19,398	26,863
Net cash provided by (used in) operating activities	66,421	44,334
Available-for-sale investments sold, matured or called:
Fixed-maturity securities — sold	6,467	14,873
Fixed-maturity securities — matured or called	108,972	105,109
Equity securities — sold	3,109
Available-for-sale investments acquired:
Equity securities — acquired	(375)	(69)
Purchases of property and equipment and other investing activities, net	(6,594)	(2,080)
Cash collateral received (returned) on loaned securities, net	12,352	(353)
Sales (purchases) of short-term investments using securities lending collateral, net	(12,352)	353
Net cash provided by (used in) investing activities	25,278	(70,020)
Cash flows from financing activities:
Dividends paid	(14,628)	(11,278)
Common stock repurchased	(53,625)	(46,328)
Tax withholdings on share-based compensation	(6,664)	(5,236)
Finance leases	(70)
Net cash provided by (used in) financing activities	(74,987)	(62,842)
Effect of foreign exchange rate changes on cash	776	(849)
Change in cash and cash equivalents	17,488	(89,377)
Cash and cash equivalents, beginning of period	262,138	279,962
Cash and cash equivalents, end of period	279,626	190,585
Fixed-maturity Securities [Member]
Available-for-sale investments acquired:
Fixed-maturity securities	$ (86,301)	$ (187,853)