Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net income	$ 143,161	$ 102,261	$ 177,530
Adjustments to reconcile net income to cash provided by operating activities:
Realized loss (gain) on sale of investments, net	89,067	(6,705)	(308,084)
Unrealized loss (gain) on investments, net	213,022	14,814	(20)
(Gain) loss on derivative instruments, net	(436,007)	(81,417)	172,290
Amortization of investment premiums, net	98,071	118,171	126,395
Other amortization and depreciation, net	2,354	2,308	1,989
Share-based compensation expense	4,419	2,516	1,823
(Increase) decrease in accrued interest receivable	(1,076)	204	11,821
Increase (decrease) in accrued interest payable	15,085	(45)	(14,175)
Change in other assets and liabilities, net	(1,744)	(5,137)	4,383
Net cash provided by operating activities	126,352	146,970	173,952
Investing activities:
Purchases of trading securities	(1,553,217)	(1,541,678)	0
Purchases of available-for-sale investments	0	0	(2,436,953)
Principal payments received on trading securities	123,982	36,515	0
Principal payments received on available-for-sale investments	225,639	394,341	474,731
Proceeds from sales of trading securities	588,651	0	0
Proceeds from sales of available-for-sale investments	95,678	472,943	4,491,873
Principal payments received on mortgage loans held for investment	1,646	2,101	2,854
Net receipts on derivatives, including terminations	453,580	86,247	(185,482)
(Decrease) increase in cash collateral posted by counterparties	(1,399)	(5,847)	5,681
Net cash (used in) provided by investing activities	(65,440)	(555,378)	2,352,704
Financing activities:
Borrowings under repurchase agreements	16,248,926	12,635,222	31,054,242
Repayments of repurchase agreement borrowings	(16,454,437)	(12,222,469)	(33,369,427)
Principal payments on non-recourse collateralized financing	0	(118)	(2,646)
Proceeds from issuance of preferred stock	0	0	107,843
Proceeds from issuance of common stock	246,882	237,130	9,891
Cash paid for redemption of preferred stock	0	(69,708)	(100,000)
Cash paid for stock issuance costs	0	(329)	0
Cash paid for common stock repurchases	0	0	(372)
Payments related to tax withholding for share-based compensation	(1,347)	(853)	(245)
Dividends paid	(72,366)	(58,895)	(52,437)
Net cash (used in) provided by financing activities	(32,342)	519,980	(2,353,151)
Net increase in cash including cash posted to counterparties	28,570	111,572	173,505
Cash including cash posted to counterparties at beginning of period	421,307	309,735	136,230
Cash including cash posted to counterparties at end of period	449,877	421,307	309,735
Supplemental Disclosure of Cash Activity:
Cash paid for interest	$ 28,527	$ 5,709	$ 46,054