Unaudited Condensed Consolidated Balance Sheets (Parenthetical) $ in Thousands	Jun. 30, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares
Fixed maturity investments trading, amortized cost | $	$ 6,424,975	$ 6,035,240
Equity securities trading, cost | $	$ 757,592	$ 791,206
Common stock, shares issued	95,523,230	100,775,256
Common stock, shares outstanding	90,796,360	96,195,482
Treasury stock (shares)	4,726,870	4,579,774