Borrowings (Details) $ in Thousands |
3 Months Ended | 12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Feb. 13, 2019
USD ($)
|
Aug. 18, 2017
USD ($)
|
Mar. 31, 2019
USD ($)
counterparty
|
Dec. 31, 2018
USD ($)
counterparty
|
Mar. 31, 2018
USD ($)
|
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| Borrowings [Line Items] | ||||||||||||
| Total secured borrowings | $ 1,949,000 | $ 1,911,000 | ||||||||||
| Concentration Risk, Reverse Repurchase Agreements | 21.00% | |||||||||||
| Number of Counterparties With Concentration Risk, Reverse Repurchase Agreements | counterparty | 1 | |||||||||||
| Number of Counterparties with Outstanding Reverse Repurchase Agreements | counterparty | 24 | 23 | ||||||||||
| Investments held with dealers as collateral | $ 1,850,000 | $ 1,790,000 | ||||||||||
| Pledged Financial Instruments, Not Separately Reported, Securities For Repurchase Agreements Unsettled | $ 20,700 | $ 86,700 | $ 86,700 | |||||||||
| Repurchase Agreements amount at risk threshold | 10.00% | 10.00% | ||||||||||
| Other secured borrowings | $ 117,315 | [1] | $ 114,100 | |||||||||
| Minimum | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Reverse Repurchase Agreements Maturity | 30 days | 30 days | ||||||||||
| Reverse Repurchase Agreements Remaining Terms | 1 day | 2 days | ||||||||||
| Reverse Repurchase Agreements Interest Rate | 0.24% | 0.23% | ||||||||||
| Maximum | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Reverse Repurchase Agreements Maturity | 180 days | 180 days | ||||||||||
| Reverse Repurchase Agreements Remaining Terms | 781 days | 871 days | ||||||||||
| Reverse Repurchase Agreements Interest Rate | 5.85% | 6.07% | ||||||||||
| Reverse repurchase agreements | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Cash collateral posted for securities sold under agreements to repurchase | [2],[3] | $ 13,900 | $ 17,000 | |||||||||
| Security Owned and Pledged as Collateral, Fair Value | 200 | 200 | ||||||||||
| Securitized residential mortgage loans | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Fair Value of Assets Transfered and Accounted for as Secured Borrowings | 296,400 | 314,200 | ||||||||||
| Secured borrowing recourse facility collateralized by unsecured loan portfolio | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Other secured borrowings | $ 11,400 | $ 13,200 | ||||||||||
| Effective interest rate on borrowing | 4.75% | 4.72% | ||||||||||
| Secured borrowing recourse facility collateralized by unsecured loan portfolio | Unsecured loans | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Fair Value of Assets Transfered and Accounted for as Secured Borrowings | $ 20,200 | $ 20,300 | ||||||||||
| Non-QM loan securitization | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Other secured borrowings | $ 282,100 | $ 297,900 | ||||||||||
| Effective interest rate on borrowing | 3.75% | 3.72% | ||||||||||
| Secured borrowing facility collateralized by unsecured loan portfolio | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Other secured borrowings | $ 105,900 | $ 101,000 | ||||||||||
| Effective interest rate on borrowing | 4.67% | 4.68% | ||||||||||
| Secured borrowing facility collateralized by unsecured loan portfolio | Unsecured loans | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Fair Value of Assets Transfered and Accounted for as Secured Borrowings | $ 157,100 | $ 149,000 | ||||||||||
| Senior Notes | ||||||||||||
| Borrowings [Line Items] | ||||||||||||
| Debt Instrument, Face Amount | $ 86,000 | $ 86,000 | ||||||||||
| Proceeds from Debt, Net of Issuance Costs | $ 84,700 | |||||||||||
| Debt Instrument, Interest Rate, Stated Percentage | 5.50% | 5.25% | ||||||||||
| Redemption percentage | 100.00% | 100.00% | ||||||||||
| Debt Instrument, Maturity Date | Sep. 01, 2022 | |||||||||||
| Effective interest rate on borrowing | 5.80% | 5.55% | ||||||||||
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