Investments - Investment Fund Consolidation (Details) (USD $)								1 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2012 Five Oaks Investment Corp [Member]	May 31, 2012 Five Oaks Investment Corp [Member]	Dec. 31, 2012 Five Oaks Investment Corp [Member] Residential Mortgage Backed Securities [Member]	Mar. 31, 2013 Five Oaks Investment Corp - Post IPO [Member]	Jun. 30, 2013 Five Oaks Investment Corp - Post IPO [Member]
Class of Warrant or Right, Outstanding								3,125,000
Investment Amount						$ 25,000,000		$ 25,000,000
Issuance of ordinary shares								8,175
Equity Method Investment, Ownership Percentage								43.80%
Percentage ownership						94.00%
Fixed maturities, at fair value	26,455,103,000	27,846,920,000					81,000,000
Amortized cost of fixed maturities	26,016,208,000	26,544,806,000					77,300,000
Asset derivative fair value	17,847,000	23,515,000			8,400,000
Cash and cash equivalents	2,420,082,000	2,618,378,000	3,311,146,000	3,825,125,000	6,000,000
Other liabilities	757,424,000	868,036,000			63,400,000
Non-controlling interest in equity of consolidated subsidiaries	1,344,500,000	1,346,325,000			1,800,000
Available-for-sale securities pledged as collateral					66,300,000
Class of Warrant or Right, Exercise Price of Warrants or Rights								15.75
Shares issued during IPO of subsidiary								4,000,000
Gross proceeds from IPO								61,000,000
Shares purchased during IPO of subsidiary								1,670,000
Deconsolidation, Gain (Loss), Amount								(1,500,000)
Investment Fund Accounted For As Subsidiary Additional Investment Amount									$ 49,200,000