Investments in Affiliates (Details) - Investment Fund Consolidation (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Investment Fund Consolidation [Line Items]
Fixed maturities, at fair value	$ 27,846,920,000	$ 26,190,025,000
Cost or Amortized cost of Fixed maturities	26,544,806,000	25,771,715,000
Cash and cash equivalents	2,618,378,000	3,825,125,000	3,022,868,000	3,643,697,000
Other liabilities	868,093,000	770,945,000
Non-controlling interest in equity of consolidated subsidiaries	1,346,325,000	1,344,472,000
Five Oaks Investment Corp [Member]
Investment Fund Consolidation [Line Items]
Investment amount	25,000,000
Percentage ownership	94.00%
Cash and cash equivalents	6,000,000
Asset derivative fair value	8,400,000
Other liabilities	63,400,000
Non-controlling interest in equity of consolidated subsidiaries	1,800,000
Securities pledged as collateral	66,300,000
Five Oaks Investment Corp [Member] | Residential Mortgage Backed Securities Member
Investment Fund Consolidation [Line Items]
Fixed maturities, at fair value	81,000,000
Cost or Amortized cost of Fixed maturities	$ 77,300,000