Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Fixed maturity investments trading, amortized cost	$ 6,858,254	$ 6,825,877
Fixed maturity investments available for sale, amortized cost	$ 12,384	$ 15,943
Preference Shares, Par Value (In dollars per share)	$ 1	$ 1
Preference Shares, Shares issued (In shares)	16,000,000	16,000,000
Preference Shares, Shares outstanding (In shares)	16,000,000	16,000,000
Common Shares, Par Value (In dollars per share)	$ 1	$ 1
Common Shares, Shares issued (In shares)	43,095,065	43,701,064
Common Shares, Shares outstanding (In shares)	43,095,065	43,701,064