Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 1,979,000	$ 1,071,000	$ 24,519,000
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Stock based compensation and equity plan amortization	605,000	431,000	142,000
Realized and unrealized (gains) losses on mortgage-backed securities	51,078,000	29,685,000	(14,159,000)
Realized and unrealized loss on interest rate swaption	(36,000)	1,648,000	4,439,000
Unrealized (gains) losses on interest rate swaps	9,499,000	0	0
Gains On TBA Securities	2,518,000	(386,000)	0
Changes in operating assets and liabilities
Accrued interest receivable	(3,022,000)	(2,279,000)	(4,652,000)
Other assets	80,000	(19,000)	(105,000)
Accrued interest payable	963,000	235,000	536,000
Other liabilities	2,279,000	184,000	678,000
Due to affiliates	101,000	135,000	248,000
NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES	47,046,000	30,705,000	11,646,000
From mortgage-backed securities investments
Purchases	(3,172,001,000)	(2,687,031,000)	(2,192,282,000)
Sales	2,002,813,000	1,832,194,000	928,009,000
Principal repayments	254,607,000	215,658,000	80,486,000
ProceedsFromSaleOfFederalHomeLoanBankStock	3,750,000	0	0
PaymentsToAcquireFederalHomeLoanBankStock	0	3,753,000	0
Increase in restricted cash	(8,220,000)	(4,940,000)	(5,344,000)
Proceeds From Net TBA Settlements	(1,401,000)	386,000	0
Purchase of interest rate swaptions, net of margin cash received	(704,000)	2,464,000	4,292,000
NET CASH USED IN INVESTING ACTIVITIES	(919,748,000)	(649,950,000)	(1,193,423,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from repurchase agreements	32,375,195,000	18,867,303,000	7,663,332,000
Principal payments on repurchase agreements	(31,380,303,000)	(18,505,141,000)	(6,545,239,000)
PaymentsForFederalHomeLoanBankAdvances	187,500,000	0	0
ProceedsFromFederalHomeLoanBankBorrowings	0	187,500,000	0
Cash dividends	(36,772,000)	(38,748,000)	(22,643,000)
Proceeds From Issuance Of Common Stock	118,328,000	83,275,000	171,295,000
Common stock repurchases		10,852,000
NET CASH PROVIDED BY FINANCING ACTIVITIES	888,948,000	583,337,000	1,266,745,000
NET INCREASE IN CASH AND CASH EQUIVALENTS	16,246,000	(35,908,000)	84,968,000
CASH AND CASH EQUIVALENTS, beginning of the period	57,229,000	93,137,000	8,169,000
CASH AND CASH EQUIVALENTS, end of the period	73,475,000	57,229,000	93,137,000
Cash paid during the period for:
Interest	$ 14,641,000	$ 7,036,000	$ 2,495,000