Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Investments
Total fixed income securities, Available for sale, Cost or amortized cost	$ 5,385,432	$ 4,864,806
Fair value for fixed income securities - held to maturity, at amortized cost	163,136	195,811
Other investments, amortized cost	$ 38,230	$ 5,967
SHAREHOLDERS' EQUITY
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized	250,000	250,000
Common stock, shares issued	122,720	120,942
Common stock, shares outstanding	104,101	114,968
Treasury stock	18,619	5,974