Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fixed maturity securities:
Available for sale, amortized cost	$ 45,688,342	$ 43,116,759
Held for investment, fair value	$ 71,113	$ 76,460
Stockholders' equity:
Preferred stock, par value (dollars per share)	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (dollars per share)	$ 1	$ 1
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	90,277,626	89,331,087
Common stock, shares outstanding	90,277,626	89,331,087
Common stock, shares held in treasury	1,598,190	2,064,727