Fair Value of Financial Instruments (Carrying Value vs Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial Assets:
Restricted cash	$ 8,839	$ 7,165
Carrying Value
Financial Assets:
MSR-related assets	302,835	399,999
Cash and cash equivalents	906,409	814,354
Restricted cash	8,839	7,165
Financial Liabilities:
Securitized debt	2,046,381	1,514,509
Convertible senior notes	225,812	225,177
Senior notes	0	100,000
Estimated Fair Value
Financial Assets:
MSR-related assets	302,835	399,999
Cash and cash equivalents	906,409	814,354
Restricted cash	8,839	7,165
Financial Liabilities:
Securitized debt	2,055,295	1,519,567
Convertible senior notes	236,053	228,287
Senior notes	0	100,031
Residential whole loans \| Carrying Value
Financial Assets:
Residential whole loans, carrying value	5,550,979	5,325,401
Residential whole loans \| Estimated Fair Value
Financial Assets:
Residential whole loans, carrying value	5,757,133	5,499,303
Financing agreements with non-mark-to-market collateral provisions \| Carrying Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	795,341	1,159,213
Financing agreements with non-mark-to-market collateral provisions \| Estimated Fair Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	795,341	1,159,213
Agreements with mark-to-market collateral provisions \| Carrying Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	1,182,900	1,124,162
Agreements with mark-to-market collateral provisions \| Estimated Fair Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	1,183,012	1,124,162
Financing agreements with mark-to-market collateral provisions \| Carrying Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	178,357	213,915
Financing agreements with mark-to-market collateral provisions \| Estimated Fair Value
Financial Liabilities:
Financing agreements with mark-to-market collateral provisions	$ 178,357	$ 213,915

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Residential Whole Loans, at Fair Value and Carrying Value

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Secured financing other than securities sold under agreements to repurchase and securities loaned.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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