CONSOLIDATED STATEMENTS OF CASH FLOWS, (Unaudited) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 2,007,000	$ 1,979,000	$ 1,071,000
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Stock based compensation and equity plan amortization	535,000	605,000	431,000
Realized and unrealized (gains) losses on mortgage-backed securities	75,769,000	51,078,000	29,685,000
Derivative, Gain (Loss) on Derivative, Net	870,000	(7,017,000)	1,262,000
Changes in operating assets and liabilities
Accrued interest receivable	(2,932,000)	(3,022,000)	(2,279,000)
Other assets	(3,000)	80,000	(19,000)
Accrued interest payable	4,690,000	963,000	235,000
Other liabilities	3,841,000	2,279,000	184,000
Due to affiliates	231,000	101,000	135,000
NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES	85,008,000	47,046,000	30,705,000
From mortgage-backed securities investments
Purchases	(6,499,153,000)	(3,172,001,000)	(2,687,031,000)
Sales	5,335,583,000	2,002,813,000	1,832,194,000
Principal repayments	365,166,000	254,607,000	215,658,000
Proceeds From Sale Of Federal Home Loan Bank Stock	3,000	3,750,000	(3,753,000)
Payments on net settlement of to-be-announced securities	(5,242,000)	(1,401,000)	386,000
Purchase of interest rate swaptions, net of margin cash received	(1,138,000)	(704,000)	2,464,000
NET CASH USED IN INVESTING ACTIVITIES	(802,505,000)	(911,528,000)	(645,010,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from repurchase agreements	54,481,746,000	32,375,195,000	18,867,303,000
Principal payments on repurchase agreements	(53,741,665,000)	(31,380,303,000)	(18,505,141,000)
ProceedsFromFederalHomeLoanBankAdvances	0	0	187,500,000
Principal payments on FHLB advances	0	187,500,000	0
Cash dividends	(67,904,000)	(36,772,000)	(38,748,000)
Proceeds From Issuance Of Common Stock, net of issuance costs	197,607,000	118,328,000	83,275,000
Payments For Repurchase Of Common Stock	0	0	10,852,000
NET CASH PROVIDED BY FINANCING ACTIVITIES	869,784,000	888,948,000	583,337,000
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	152,287,000	24,466,000	(30,968,000)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of period	94,425,000	69,959,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period	246,712,000	94,425,000	69,959,000
Cash paid during the period for:
Interest Paid	36,981,000	14,641,000	7,036,000
Interest Rate Swaption [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Derivative, Gain (Loss) on Derivative, Net	(1,038,000)	(36,000)	1,648,000
Swap [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Derivative, Gain (Loss) on Derivative, Net	(4,030,000)	(9,499,000)	0
TBA Contracts [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Derivative, Gain (Loss) on Derivative, Net	$ 5,938,000	$ 2,518,000	$ (386,000)