DERIVATIVES - Schedule of Derivatives - Notional Amount (Details) - Not Designated as Hedging Instrument [Member] - USD ($)		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Long [Member]
Derivative [Line Items]
Derivative liability, notional amount		$ 1,800,000,000
TBAs [Member] | Short [Member]
Derivative [Line Items]
Derivative liability, notional amount	[1]	3,686,000,000	$ 3,465,500,000
TBAs [Member] | Long [Member]
Derivative [Line Items]
Derivative liability, notional amount	[1]	2,361,000,000	2,125,552,000
Interest Rate Caps [Member]
Derivative [Line Items]
Derivative asset, notional amount	[2]	$ 910,000,000	1,185,000,000
Weighted average maturity (in months)		17 months
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative liability, notional amount	[3]	$ 5,525,500,000	$ 3,640,000,000
Weighted average maturity (in months)		25 months
Weighted average fixed pay rate		1.51%
Interest Rate Cap, Contract One [Member]
Derivative [Line Items]
Derivative, cap interest rate		0.50%
Notional amount of derivatives		$ 550,000,000
Interest Rate Cap, Contract Two [Member]
Derivative [Line Items]
Derivative, cap interest rate		0.75%
Notional amount of derivatives		$ 25,000,000
Interest Rate Cap, Contract Three [Member]
Derivative [Line Items]
Derivative, cap interest rate		2.00%
Notional amount of derivatives		$ 185,000,000
Interest Rate Cap, Contract Four [Member]
Derivative [Line Items]
Derivative, cap interest rate		4.00%
Notional amount of derivatives		$ 150,000,000

[1] Represents the notional amount of Agency RMBS, classified as derivatives.

[2] Caps LIBOR at 0.50% for $550.0 million of notional, at 0.75% for $25.0 million of notional, at 2.00% for $185.0 million of notional, and at 4.00% for $150.0 million of notional. The weighted average maturity of the interest rate caps as of March 31, 2017 was 17 months.

[3] Receive LIBOR and pay a fixed rate. The weighted average maturity of the interest rate swaps as of March 31, 2017 was 25 months and the weighted average fixed pay rate was 1.51%.