Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Amortized cost on fixed maturities trading investments	$ 2,413,895	$ 2,270,903
Cost - equity security trading investments	492,573	475,959
Cost - short-term investments	$ 165,783	$ 294,607
Common Stock
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	54,959,000	54,922,000
Common stock, shares outstanding	54,959,000	54,922,000