Reinsurance (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reinsurance [Abstract]
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount	$ 76,000,000	$ 76,000,000	$ 74,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies	2,927,573,000,000	2,664,353,000,000	2,540,317,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	38,048,000,000	39,987,000,000	42,582,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 2,889,601,000,000	$ 2,624,442,000,000	$ 2,497,809,000,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	101.31%	101.52%	101.70%