Investments - Investment Fund Consolidation (Details) (USD $)							3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 Five Oaks Investment Corp [Member]	Mar. 31, 2013 Five Oaks Investment Corp [Member] Residential Mortgage Backed Securities [Member]	Mar. 31, 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	27,349,185,000	27,846,920,000				81,000,000
Amortized cost of fixed maturities	26,188,523,000	26,544,806,000				77,300,000
Asset derivative fair value					8,400,000
Cash and cash equivalents	2,473,287,000	2,618,378,000	2,506,318,000	3,825,125,000	6,000,000
Other liabilities	895,417,000	868,093,000			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