Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Amortized cost on fixed maturities trading investments	$ 2,804,605	$ 2,503,494
Cost - equity security trading investments	307,857	387,851
Cost - short-term investments	$ 153,549	$ 373,180
Common Stock
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	55,164,000	55,121,000
Common stock, shares outstanding	55,164,000	55,121,000