Financings - Narrative (Details)									1 Months Ended		12 Months Ended
	Nov. 05, 2021 USD ($)	Nov. 04, 2021	May 05, 2021 USD ($)	Oct. 06, 2020	Jul. 01, 2020 USD ($) $ / shares shares	Jun. 29, 2020 USD ($)	May 04, 2020	Apr. 21, 2020 counterparty	Sep. 30, 2021 USD ($) $ / shares	May 31, 2019 USD ($)	Dec. 31, 2021 USD ($) agreement item $ / shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($)	Aug. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)
Short-term Debt [Line Items]
Number of longer term financial arrangements company entered to reduce its exposure to short term financings | agreement											3
Number of counterparties from whom the Company had borrowings | item											5
Financing fee											$ (8,540,000)	$ (12,000,000.0)	$ 0
Repurchase Agreement Borrowings											617,189,000	358,846,000
Assets pledged											5,207,000	12,960,000
Due from counterparties											3,200,000	1,800,000
Due to counterparties											$ 0	$ 320,000
Common stock, par value (in dollars per share) | $ / shares											$ 0.01	$ 0.01
Repurchase agreements, net											$ 617,189,000	$ 356,923,000
Repurchase Agreements
Short-term Debt [Line Items]
Repurchase Agreement Borrowings											$ 563,132,000	$ 250,248,000
Weighted average interest rate											2.24%	3.74%
Residential Whole Loans | Repurchase Agreements
Short-term Debt [Line Items]
Repurchase Agreement Borrowings											$ 396,500,000
Commercial Loans | Repurchase Agreements
Short-term Debt [Line Items]
Repurchase Agreement Borrowings											$ 63,661,000	$ 124,937,000
Weighted average interest rate											2.27%	2.17%
Commercial Loans | Securities Sold Under Agreements To Repurchase
Short-term Debt [Line Items]
Weighted average interest rate											2.27%
Arroyo Mortgage Trust 2020 | Secured Debt
Short-term Debt [Line Items]
Principal balance											$ 183,577,000
Outstanding principle balance											181,547,000
Arroyo Mortgage Trust 2020 | Non-QM Loans | Arroyo Trust
Short-term Debt [Line Items]
Number of counterparties from whom the Company had borrowings | counterparty								3
Target advance rate								84.00%
Commitment fee percentage								30.00%
Exit fee percentage								0.50%
Line of credit, remaining borrowing capacity											451,700,000
Arroyo Mortgage Trust 2020 | Residential Whole Loans, at Fair Value
Short-term Debt [Line Items]
Repurchase agreements, net															$ 341,700,000		$ 341,700,000
Arroyo Mortgage Trust 2020 | Residential Whole Loans, at Fair Value | Secured Debt
Short-term Debt [Line Items]
Outstanding principle balance											$ 188,200,000
Debt instrument, collateral balance percentage											30.00%
Debt Instrument, Term, Redemption Of Offering Notes											3 years
Arroyo Mortgage Trust 2020 | Residential Whole Loans, at Fair Value | Arroyo Trust
Short-term Debt [Line Items]
Commitment fee percentage						30.00%
Line of credit facility, maximum borrowing capacity						$ 355,800,000
Repayments of Lines of Credit	$ 8,500,000					$ 339,400,000
Debt Instrument, Fee						20.5 million
Arroyo Mortgage Trust 2019-2 | Residential Whole Loans, at Fair Value
Short-term Debt [Line Items]
Repurchase agreements, net											$ 919,000,000
Arroyo Mortgage Trust 2019-2 | Residential Whole Loans, at Fair Value | Arroyo Trust
Short-term Debt [Line Items]
Transfer of residential mortgage-backed securitization										$ 945,500,000
CSMC Trust
Short-term Debt [Line Items]
Trust certificates issued											1,400,000,000
CSMC Trust | Affiliated Entity
Short-term Debt [Line Items]
Trust certificates issued											198,300,000
CSMC Trust | Third Party
Short-term Debt [Line Items]
Trust certificates issued											1,200,000,000
CSMC Trust | Secured Debt
Short-term Debt [Line Items]
Principal balance											1,370,691,000
Debt Instrument, Fair Value Disclosure											1,344,370,000
CSMC Trust | Securitized Commercial Loans
Short-term Debt [Line Items]
Financing receivable, gross											1,400,000,000
Arroyo Trust | Residential Whole Loans, at Fair Value | Secured Debt
Short-term Debt [Line Items]
Outstanding principle balance											$ 358,900,000
Debt instrument, collateral balance percentage											20.00%
Debt Instrument, Term, Redemption Of Offering Notes											3 years
Residential Loan Warehouse Facility
Short-term Debt [Line Items]
Target advance rate				85.00%
Residential Loan Warehouse Facility | London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	2.00%			2.75%
Residential Loan Warehouse Facility | Non-QM Loans
Short-term Debt [Line Items]
Target advance rate		90.00%
Line of credit, remaining borrowing capacity	$ 500,000,000
Non-Agency CMBS and Non-Agency RMBS Facility
Short-term Debt [Line Items]
Debt instrument, term			12 months				12 months
Debt Instrument, Term Extensions At Counterparty’s Option							12 months
Loans Pledged as Collateral											$ 181,000,000.0
Line of credit, remaining borrowing capacity											$ 102,900,000
Non-Agency CMBS and Non-Agency RMBS Facility | London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate			2.00%				5.00%
2022 Notes | Convertible Debt
Short-term Debt [Line Items]
Principal balance					$ 5,000,000
Redemption price, percentage									100.00%
Convertible senior unsecured notes, conversion price (in dollars per share) | $ / shares									$ 2.96
Exchange of convertible senior notes (in shares) | shares					1,354,084
Convertible senior unsecured notes, conversion ratio											0.337952
Class F | CSMC Trust | Secured Debt
Short-term Debt [Line Items]
Principal balance											$ 153,600,000
Debt Instrument, Fair Value Disclosure											117,912,000
Debt default, amount											14,900,000
Class F | CSMC Trust | Secured Debt | Estimate of Fair Value Measurement
Short-term Debt [Line Items]
Debt Instrument, Fair Value Disclosure											1,300,000,000
Commercial Whole Loan Facility
Short-term Debt [Line Items]
Debt instrument, term			12 months
Debt Instrument, Term Extensions At Counterparty’s Option			12 months
Commercial Whole Loan Facility | Estimate of Fair Value Measurement
Short-term Debt [Line Items]
Loans Pledged as Collateral											87,100,000
Commercial Whole Loan Facility | Repurchase Agreements
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity			$ 100,000,000
Commercial Whole Loan Facility | Securities Sold Under Agreements To Repurchase
Short-term Debt [Line Items]
Outstanding principle balance											63,700,000
Six Point Seventy Five Percent Convertible Senior Unsecured Notes Due 2022
Short-term Debt [Line Items]
Debt instrument, repurchase amount									$ 100,300,000		$ 8,000,000.0	$ 25,000,000		$ 22,300,000		$ 6,700,000
Debt instrument, interest rate, effective percentage											1.00%	13.00%		2.80%		6.30%
Six Point Seventy Five Percent Convertible Senior Unsecured Notes Due 2022 | Convertible Debt
Short-term Debt [Line Items]
Principal balance					$ 5,000,000						$ 37,700,000	$ 175,000,000
Interest rate, stated percentage											6.75%
Redemption price, percentage											100.00%
Convertible senior unsecured notes, conversion price (in dollars per share) | $ / shares											$ 12.02
Exchange of convertible senior notes (in shares) | shares					1,354,084
Common stock, par value (in dollars per share) | $ / shares					$ 0.01
Convertible senior unsecured notes, conversion ratio											0.0831947000
Minimum | Repurchase Agreements
Short-term Debt [Line Items]
Debt instrument, term											1 month
Minimum | Residential Loan Warehouse Facility | London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	0.25%			0.25%
Maximum | Repurchase Agreements
Short-term Debt [Line Items]
Debt instrument, term											12 months