To Be Announced RMBS (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
To Be Announced Securities [Line Items]
Fair Value	$ 2,172,082,000		$ 1,730,130,000
Receivable for securities sold	1,237,592,000		883,005,000
Financial Instruments Sold, Not yet Purchased, at Fair Value	(1,291,370,000)		(845,614,000)
Payable for securities purchased	98,747,000		193,047,000
To Be Announced Fixed Rate Agency Securities [Member]
To Be Announced Securities [Line Items]
Fair Value	72,410,000	[1],[2],[3],[4]	96,856,000	[1],[5],[6],[7]
Investment Owned, Balance, Principal Amount	71,598,000		101,150,000
Receivable for securities sold	1,205,779,000		813,933,000
TBA - Fixed Rate Agency Securities Sold Short [Member]
To Be Announced Securities [Line Items]
Financial Instruments Sold, Not yet Purchased, at Fair Value	(1,209,539,000)	[1],[2],[8]	(811,957,000)	[1],[7],[9]
Investment Sold, Not yet Purchased, Balance, Principal Amount	(1,135,218,000)		(784,888,000)
Payable for securities purchased	(71,832,000)		(96,762,000)
Investment Owned At Fair Value, Net	$ (1,137,129,000)		$ (715,101,000)

[1] See Note 2 and Note 3 in Notes to Consolidated Financial Statements.

[2] The following table details the breakout by geographical region of long investments, investments sold short, repurchase agreements, financial derivatives–assets, and financial derivatives–liabilities.Region Current Principal/Notional Value/Number of Properties/Number of Shares Cost/(Proceeds) Fair Value Percent ofEquityLong Investments: (In thousands, Expressed in U.S. Dollars) North America 2,863,057 $2,038,249 $2,092,959 264.46 %Europe 69,724 69,360 64,611 9.16 %North America (Private Corporate Investments) n/a 14,717 14,512 1.84 %Total $2,122,326 $2,172,082 275.46 %Investments Sold Short: North America (TBAs and Government Debt) (1,159,703) $(1,230,478) $(1,234,248) (156.53)%Europe (Government Debt) (28,118) (32,008) (30,606) (3.88)%North America (Common Stock) (2,986) (27,605) (26,516) (3.36)%Total $(1,290,091) $(1,291,370) (163.77)%Repurchase Agreements: North America 140,248 $140,248 $140,248 17.78 %Europe 31,753 31,753 31,753 4.03 %Total 172,001 $172,001 $172,001 21.81 %Financial Derivatives–Assets: North America 1,401,261 $61,560 $80,029 10.15 %Europe — — — — %Total 1,401,261 $61,560 $80,029 10.15 %Financial Derivatives–Liabilities: North America (936,799) $(30,598) $(63,084) (8.00)%Europe (37,199) (2,957) (3,032) (0.39)%Total (973,998) $(33,555) $(66,116) (8.39)%

[3] At December 31, 2014, the Company's long investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association, represented 100.30%, 53.97%, and 9.33% of equity, respectively.

[4] The table below shows the Company's long investment ratings from Moody's, Standard and Poor's, or Fitch, as well as the Company's long investments that were unrated but guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or the Government National Mortgage Association. Ratings tend to be a lagging credit indicator; as a result, the credit quality of the Company's long investment holdings may be lower than the credit quality implied based on the ratings listed below. In situations where an investment has a split rating, the lowest provided rating is used. The ratings descriptions include ratings qualified with a "+," "-," "1," "2," or "3."Rating Description Percent of EquityUnrated but Agency-Guaranteed 163.60%A/A/A 0.98%Baa/BBB/BBB 5.62%Ba/BB/BB or below 80.65%Unrated 24.61%

[5] At December 31, 2013, the Company's long investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association, represented 100.85%, 51.37%, and 12.36% of equity, respectively.

[6] The table below shows the ratings on the Company's long investments from Moody's, Standard and Poor's, or Fitch, as well as the Company's long investments that were unrated but guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or the Government National Mortgage Association. Ratings tend to be a lagging credit indicator; as a result, the credit quality of the Company's long investment holdings may be lower than the credit quality implied based on the ratings listed below. In situations where an investment has a split rating, the lowest provided rating is used. The ratings descriptions include ratings qualified with a "+," "-," "1," "2," or "3."Rating Description Percent ofEquityUnrated but Agency-Guaranteed 164.58%A/A/A 0.34%Baa/BBB/BBB 2.97%Ba/BB/BB or below 97.95%Unrated 10.52%

[7] The following table details the breakout by geographical region of long investments, investments sold short, and repurchase agreements. All financial derivatives were concentrated in North America.Region Current Principal/Notional Value/Number of Shares Cost/(Proceeds) Fair Value Percent ofEquityLong Investments: (In thousands, Expressed in U.S. Dollars) North America 2,470,650 $1,682,533 $1,724,370 275.44 %Europe 7,641 5,724 5,760 0.92 %Total 2,478,291 $1,688,257 $1,730,130 276.36 %Investments Sold Short: North America (TBAs and Government Debt) (804,888) $(833,656) $(831,564) (132.82)%Europe (Government Debt) (7,337) (7,633) (7,681) (1.23)%North America (Common Stock) (763) (6,313) (6,369) (1.02)%Total $(847,602) $(845,614) (135.07)%Repurchase Agreements: North America 19,675 $19,675 $19,675 3.15 %Europe 8,287 8,268 8,287 1.32 %Total 27,962 $27,943 $27,962 4.47 %

[8] At December 31, 2014, the Company's short investments guaranteed by the Federal National Mortgage Association and the Federal Home Loan Mortgage Corporation, represented 121.95% and 31.44% of equity, respectively.

[9] At December 31, 2013, the Company's short investments guaranteed by the Federal National Mortgage Association and the Federal Home Loan Mortgage Corporation represented 111.89% and 17.80% of equity, respectively.