Unaudited Condensed Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Balance Sheet Parenthetical Disclosure Assets
Fixed maturities, trading securities, amortized cost	$ 13,811,342	$ 13,394,404
Short-term investments, trading securities, amortized cost	38,819	42,563
Equities, trading securities, cost	865,452	917,613
Funds held - directly managed, cost	1,230,199	1,241,222
Balance Sheet Parenthetical Disclosures Equity
Common shares, par value	$ 1	$ 1
Common shares, shares issued	84,939,858	84,766,693
Other accumulated comprehensive (loss) income, tax	6,780	6,590
Common shares held in treasury, shares	19,626,865	19,444,365
Preferred shares, par value	$ 1	$ 1
Preferred shares, shares issued	35,750,000	35,750,000
Preferred shares, shares outstanding	35,750,000	35,750,000
Aggregate liquidation value	$ 893,750	$ 893,750