Condensed Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets [Abstract]
Fixed maturities, trading securities, amortized cost	$ 13,110,735	$ 13,653,615
Short-term investments, trading securities, amortized cost	29,392	150,634
Equities, trading securities, cost	1,086,846	1,000,326
Funds held - directly managed, cost	828,646	895,261
Stockholders Equity [Abstract]
Common shares, par value	$ 1	$ 1
Common shares, shares issued	86,364,643	85,459,905
Common shares held in treasury, shares	32,042,911	26,550,530
Preferred shares, par value	$ 1	$ 1
Preferred shares, shares issued	34,150,000	35,750,000
Preferred shares, shares outstanding	34,150,000	35,750,000
Aggregate liquidation value	$ 853,750	$ 893,750