Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net income (loss)	$ 117,929	$ (98,479)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
(Gain) loss on derivative instruments, net	(107,801)	195,567
Gain on sale of investments, net	(4,697)	(84,783)
Loss on investments, net	980	372
Amortization of investment premiums, net	30,161	33,118
Other amortization and depreciation, net	599	499
Stock-based compensation expense	452	307
(Increase) decrease in accrued interest receivable	(1,092)	3,105
Decrease in accrued interest payable	(992)	(5,979)
Change in other assets and liabilities, net	(5,350)	254
Net cash provided by operating activities	30,189	43,981
Investing activities:
Purchase of investments	(68,543)	(155,594)
Principal payments received on investments	118,022	140,032
Proceeds from sales of investments	220,194	487,464
Principal payments received on mortgage loans held for investment	488	615
Net receipts (payments) on derivatives, including terminations	52,079	(187,822)
Increase (Decrease) Cash Collateral from Counterparties	76,095	3,185
Net cash provided by investing activities	398,335	287,880
Financing activities:
Borrowings under repurchase agreements	4,494,067	16,555,552
Repayments of repurchase agreement borrowings	(4,899,141)	(16,899,794)
Principal payments on non-recourse collateralized financing	(118)	(569)
Proceeds from issuance of preferred stock	0	107,988
Proceeds from issuance of common stock	128,150	0
Payments for Repurchase of Redeemable Preferred Stock	(69,708)	(100,000)
Cash paid for stock issuance costs	(270)	0
Payments for Repurchase of Common Stock	0	206
Payments related to tax withholding for stock-based compensation	(428)	(235)
Dividends paid	(13,320)	(15,027)
Net cash used in financing activities	(360,768)	(352,291)
Net increase (decrease) in cash and cash posted to counterparties	67,756	(20,430)
Cash and cash posted to counterparties at beginning of period	310,360	136,230
Cash and cash posted to counterparties at end of period	378,116	115,800
Supplemental Disclosure of Cash Activity:
Cash paid for interest	$ 2,619	$ 28,074