Short-Term Debt - Collateral for Short-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Total Collateral for Short-Term Debt Facilities	$ 2,450,304	$ 649,106
Line of Credit
Short-term Debt [Line Items]
Total real estate securities owned	99,005	114,553
Other assets	1,962	315
Total Collateral for Short-Term Debt Facilities	2,107,451	398,252
Servicer advance financing
Short-term Debt [Line Items]
Total Collateral for Short-Term Debt Facilities	342,853	250,854
Cash Collateral for Borrowed Securities	6,480	9,978
Restricted Cash Collateral For Borrowed Securities	25,420	23,220
Servicer Advances Collateral	310,953	217,656
On balance sheet \| Line of Credit
Short-term Debt [Line Items]
On balance sheet	5,823	23,193
Sequoia \| Sequoia securities \| Short Term Borrowing Agreement \| Line of Credit
Short-term Debt [Line Items]
Trading securities pledged as collateral	61,525	63,105
Freddie Mac K-Series \| Sequoia securities \| Short Term Borrowing Agreement \| Line of Credit
Short-term Debt [Line Items]
Trading securities pledged as collateral	31,657	28,255
Residential loans, held-for-sale, at fair value \| Line of Credit
Short-term Debt [Line Items]
Loan pledged as collateral	1,838,797	156,355
Business Purpose Loans \| Line of Credit
Short-term Debt [Line Items]
Loan pledged as collateral	$ 167,687	$ 127,029

Other Assets Pledged as Collateral

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- Definition

Restricted Cash Collateral For Borrowed Securities

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Servicer Advances Collateral

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- Definition

Short-term Debt Pledged as Collateral

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Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage.

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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The sum of the fair values, as of the date of each statement of financial position presented, of securities that are restricted as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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