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Commitments and Contingencies - Additional Information (Details) $ in Thousands |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended | 48 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2019 USD ($) lease | Dec. 31, 2018 USD ($) | Jul. 15, 2010 plaintiff | Dec. 31, 2018 USD ($) partnership | Sep. 30, 2019 USD ($) | Dec. 31, 2019 USD ($) loan lease certificate repurchase_request | Dec. 31, 2018 USD ($) loan repurchase_request | Dec. 31, 2017 USD ($) loan | Dec. 31, 2007 certificate | Dec. 31, 2004 certificate | Dec. 31, 2007 certificate | Mar. 01, 2019 USD ($) | Jan. 01, 2019 USD ($) lease | May 31, 2018 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 23, 2009
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lessee, number of leases | lease | 8 |  |  |  |  | 8 |  |  |  |  |  |  |  |  |  |  |
Future lease commitments with expiration date | $ 16,000 |  |  |  |  | $ 16,000 |  |  |  |  |  |  |  |  |  |  |
Operating lease expense |  |  |  |  |  | 3,000 |  |  |  |  |  |  |  |  |  |  |
Operating lease expense |  |  |  |  |  |  | $ 2,000 | $ 2,000 |  |  |  |  |  |  |  |  |
Unamortized leasehold improvements | 3,000 |  |  |  |  | 3,000 |  |  |  |  |  |  |  |  |  |  |
Leasehold amortization expense (less than) |  |  |  |  |  | 400 | 200 | 200 |  |  |  |  |  |  |  |  |
Present value of remaining lease payments | 16,132 |  |  |  |  | $ 16,132 |  |  |  |  |  |  | $ 16,000 |  |  |  |
Number of leases noncancelable | lease |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |  |
Number of leases | lease |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |
Number of new leases | lease |  |  |  |  |  | 5 |  |  |  |  |  |  |  |  |  |  |
Lease liability | 13,443 | $ 0 |  | $ 0 |  | $ 13,443 | 0 |  |  |  |  |  |  |  |  |  |
Right-of-use asset | $ 11,866 | 0 |  | $ 0 |  | $ 11,866 | 0 |  |  |  |  |  |  |  |  |  |
Number of leases without implicit interest rate | lease |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
Weighted average remaining lease term | 7 years |  |  |  |  | 7 years |  |  |  |  |  |  |  |  |  |  |
Discount rate | 5.30% |  |  |  |  | 5.30% |  |  |  |  |  |  |  |  |  |  |
Number of partnerships, committed to fund | partnership |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to fund partnership |  | 71,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration | $ 28,484 | 0 |  | $ 0 |  | $ 28,484 | 0 |  |  |  |  |  |  |  |  |  |
Risk share income |  |  |  |  |  | 3,522 | 3,613 | $ 3,194 |  |  |  |  |  |  |  |  |
Principal amount outstanding on loans securitized | 524,928 | 1,034,284 |  | 1,034,284 |  | 524,928 | 1,034,284 |  |  |  |  |  |  |  |  |  |
Guarantee obligations | 14,009 | 16,711 |  | 16,711 |  | 14,009 | 16,711 |  |  |  |  |  |  |  |  |  |
Guarantee obligation, credit reserve | 5,000 |  |  |  |  | 5,000 |  |  |  |  |  |  |  |  |  |  |
SPE, assets | 48,000 | 47,000 |  | 47,000 |  | 48,000 | 47,000 |  |  |  |  |  |  |  |  |  |
SPE, liabilities | 14,000 | 17,000 |  | 17,000 |  | 14,000 | 17,000 |  |  |  |  |  |  |  |  |  |
Residential loan and MSR repurchase reserve | 4,268 | 4,189 |  | 4,189 |  | $ 4,268 | $ 4,189 |  |  |  |  |  |  |  |  |  |
Residential loans repurchase requests | repurchase_request |  |  |  |  |  | 15 | 11 |  |  |  |  |  |  |  |  |  |
Residential loans, number of loans repurchased | loan |  |  |  |  |  | 0 | 2 | 1 |  |  |  |  |  |  |  |  |
Residential loans repurchase provision (reversal) |  |  |  |  |  | $ 100 | $ 700 | $ 300 |  |  |  |  |  |  |  |  |
Residential loans repurchased during period |  |  |  |  |  | 0 | 0 | 200 |  |  |  |  |  |  |  |  |
Aggregate amount of loss contingency reserves | 2,000 | 2,000 |  | 2,000 |  | $ 2,000 | 2,000 |  |  |  |  |  |  |  |  |  |
Morgan Stanley and Company |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of mortgage pass through certificates issued | certificate |  |  |  |  |  | 28 |  |  |  |  |  |  |  |  |  |  |
Sequoia Residential Funding |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of mortgage pass through certificates issued | certificate |  |  |  |  |  |  |  |  | 2 | 2 | 4 |  |  |  |  |  |
Schwab |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of other named defendants along with SRF | plaintiff |  |  | 26 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount outstanding on loans securitized | 525,000 | $ 1,030,000 |  | $ 1,030,000 |  | $ 525,000 | 1,030,000 |  |  |  |  |  |  |  |  |  |
Loans held as assets amount in foreclosure | 2,000 |  |  |  |  | 2,000 |  |  |  |  |  |  |  |  |  |  |
Other Income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk share income |  |  |  |  |  | 4,000 | 4,000 | 3,000 |  |  |  |  |  |  |  |  |
Mortgage Banking And Investment Activities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Market valuation changes in fair value of guarantee asset |  |  |  |  |  | 200 | $ 400 | $ 1,000 |  |  |  |  |  |  |  |  |
Guarantee Obligations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Original principal balance of loans sold subject to risk sharing agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,190,000 | $ 3,190,000 |
Potential future payments on risk sharing agreements | 44,000 |  |  |  |  | 44,000 |  |  |  |  |  |  |  |  |  |  |
Principal amount outstanding on loans securitized | $ 1,550,000 |  |  |  |  | $ 1,550,000 |  |  |  |  |  |  |  |  |  |  |
FICO credit score | 759 |  |  |  |  | 759 |  |  |  |  |  |  |  |  |  |  |
Loan to value ratio | 76.00% |  |  |  |  | 76.00% |  |  |  |  |  |  |  |  |  |  |
Guarantee Obligations | Financing Receivables, Equal to Greater than 90 Days Past Due |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans past due | $ 7,000 |  |  |  |  | $ 7,000 |  |  |  |  |  |  |  |  |  |  |
Residential | Sequoia Entities | FHLB Seattle |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Statutory interest rate per annum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8.00%
Original principal amount of securities | 133,000 |  |  |  |  | 133,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument principal payment amount |  |  |  |  |  | 128,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument interest payment amount |  |  |  |  |  | 12,000 |  |  |  |  |  |  |  |  |  |  |
Residential | Sequoia Entities | Schwab |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Original principal amount of securities | 15,000 |  |  |  |  | 15,000 |  |  |  |  |  |  |  |  |  |  |
Principal balance of securities | 14,000 |  |  |  |  | 14,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument interest amount | 1,000 |  |  |  |  | 1,000 |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to fund partnership | 37,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Guarantor obligations carrying value | 100 |  |  |  |  | 100 |  |  |  |  |  |  |  |  |  |  |
Guarantee obligations expenses | 135,000 |  |  |  |  | 135,000 |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2016-02 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease liability | 13,000 |  |  |  |  | 13,000 |  |  |  |  |  |  |  |  |  |  |
Right-of-use asset | 12,000 |  |  |  |  | 12,000 |  |  |  |  |  |  |  |  |  |  |
Commitment To Fund Residential Bridge Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitments to fund temporary advances | 173,000 |  |  |  |  | 173,000 |  |  |  |  |  |  |  |  |  |  |
Commitment To Fund Temporary Advances On Residential Bridge Loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitments to fund temporary advances | 56,000 |  |  |  |  | 56,000 |  |  |  |  |  |  |  |  |  |  |
Shared home appreciation options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire investments | 43,000 |  |  |  |  | 45,000 |  |  |  |  |  |  |  |  |  |  |
Shared home appreciation options | Commitment To Fund Investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitments to fund temporary advances | 7,000 |  |  |  |  | 7,000 |  |  |  |  |  |  |  |  |  |  |
5 Arches, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration maximum amount |  |  |  |  |  |  |  |  |  |  |  | $ 27,000 |  | $ 29,000 |  |  |
Contingent consideration | $ 28,000 |  |  |  |  | $ 28,000 |  |  |  |  |  | $ 24,621 |  |  |  |  |
Contingent consideration expense |  |  |  |  | $ 3,000 |  |  |  |  |  |  |  |  |  |  |  |

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