CONSOLIDATED STATEMENTS OF CASH FLOWS, (Unaudited) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 24,265,000	$ (44,387,000)	$ 2,007,000
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Stock based compensation and equity plan amortization	294,000	492,000	535,000
Realized and unrealized (gains) losses on mortgage-backed securities	(27,168,000)	140,957,000	75,769,000
Derivative, Gain (Loss) on Derivative, Net	45,207,000	(4,052,000)	870,000
Changes in operating assets and liabilities
Accrued interest receivable	837,000	1,203,000	(2,932,000)
Other assets	80,000	(3,000)	(3,000)
Accrued interest payable	4,656,000	(71,000)	4,690,000
Other liabilities	22,000	4,000	3,841,000
Due to affiliates	(32,000)	(143,000)	231,000
NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES	48,161,000	94,000,000	85,008,000
From mortgage-backed securities investments
Purchases	(4,241,822,000)	(3,893,828,000)	(6,499,153,000)
Sales	3,321,206,000	3,885,817,000	5,335,583,000
Principal repayments	594,833,000	373,934,000	365,166,000
Proceeds From Sale Of Federal Home Loan Bank Stock	0	0	3,000
Payments on net settlement of to-be-announced securities	(8,423,000)	7,292,000	(5,242,000)
Purchase of interest rate swaptions, net of margin cash received	20,600,000	(6,805,000)	(1,138,000)
NET CASH USED IN INVESTING ACTIVITIES	(354,806,000)	380,020,000	(802,505,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from repurchase agreements	45,595,010,000	52,096,292,000	54,481,746,000
Principal payments on repurchase agreements	(45,171,956,000)	(52,605,026,000)	(53,741,665,000)
Cash dividends	(53,307,000)	(59,312,000)	(67,904,000)
Proceeds From Issuance Of Common Stock, net of issuance costs	92,314,000	0	197,607,000
Payments For Repurchase Of Common Stock	3,024,000	26,423,000	0
NET CASH PROVIDED BY FINANCING ACTIVITIES	459,037,000	(594,469,000)	869,784,000
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	152,392,000	(120,449,000)	152,287,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of period	126,263,000	246,712,000	94,425,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period	278,655,000	126,263,000	246,712,000
Cash paid during the period for:
Interest Paid	79,010,000	70,431,000	36,981,000
SUPPLEMENTAL DISCLOSURES OF NONCASH FINANCING ACTIVITIES:
Securities Sold Settled In Later Period	0	220,655,000	0
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	1,379,000	1,502,000	(1,038,000)
Swap [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Derivative, Gain (Loss) on Derivative, Net	39,471,000	(1,027,000)	(4,030,000)
TBA Contracts [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Derivative, Gain (Loss) on Derivative, Net	$ 4,357,000	$ (4,527,000)	$ 5,938,000