CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 12,023,304	$ 11,987,146
Equity securities, available for sale, cost	581,473	566,219
Short term investments, amortized cost	$ 296,800	$ 46,212
Common shares, shares issued	175,195	174,134
Common shares, shares outstanding	106,745	109,485
Treasury shares, shares	68,450	64,649