Secured Financing Agreements - Summary of Outstanding Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Line of Credit Facility [Line Items]
Repurchase facilities	$ 1,271,659	$ 677,285
Asset-specific financings	43,622	43,622
Term financing facility	0	127,145
Unused Capacity	528,341	1,122,715
Total Capacity	1,800,000	1,800,000
Carrying Value of Collateral	1,813,360	1,054,842
Goldman Sachs Bank USA
Line of Credit Facility [Line Items]
Term financing facility	0	127,145
Unused Capacity		0
Total Capacity		127,145
Goldman Sachs Bank USA | Revolving Credit Facility
Line of Credit Facility [Line Items]
Carrying Value of Collateral		$ 329,256
Weighted Average Borrowing Rate		3.70%
CIBC Bank USA
Line of Credit Facility [Line Items]
Asset-specific financings	43,622	$ 43,622
Unused Capacity	106,378	106,378
Total Capacity	150,000	150,000
CIBC Bank USA | Secured Debt
Line of Credit Facility [Line Items]
Carrying Value of Collateral	$ 57,794	$ 56,129
Weighted Average Borrowing Rate	3.00%	1.80%
Loans held-for-investment | Morgan Stanley Bank
Line of Credit Facility [Line Items]
Repurchase facilities	$ 581,440	$ 230,982
Unused Capacity	18,560	269,018
Total Capacity	600,000	500,000
Carrying Value of Collateral	$ 802,912	$ 382,017
Weighted Average Borrowing Rate	3.80%	2.20%
Maximum capacity under collateralized borrowings upon exercise of option to increase	$ 600,000
Loans held-for-investment | Goldman Sachs Bank USA
Line of Credit Facility [Line Items]
Repurchase facilities	127,725	$ 81,227
Unused Capacity	122,275	168,773
Total Capacity	250,000	250,000
Carrying Value of Collateral	$ 204,600	$ 111,811
Weighted Average Borrowing Rate	4.00%	2.60%
Maximum capacity under collateralized borrowings upon exercise of option to increase	$ 350,000
Loans held-for-investment | JPMorgan Chase Bank (4)
Line of Credit Facility [Line Items]
Repurchase facilities	177,228	$ 104,215
Unused Capacity	172,772	345,785
Total Capacity	350,000	450,000
Carrying Value of Collateral	$ 276,366	$ 188,838
Weighted Average Borrowing Rate	3.70%	2.30%
Maximum capacity under collateralized borrowings upon exercise of option to increase	$ 350,000
Loans held-for-investment | Citibank (5)
Line of Credit Facility [Line Items]
Repurchase facilities	285,266	$ 202,944
Unused Capacity	214,734	297,056
Total Capacity	500,000	500,000
Carrying Value of Collateral	$ 378,217	$ 285,767
Weighted Average Borrowing Rate	3.20%	1.80%
Loans held-for-investment | Wells Fargo Bank
Line of Credit Facility [Line Items]
Repurchase facilities	$ 100,000	$ 57,917
Unused Capacity	0	42,083
Total Capacity	100,000	100,000
Carrying Value of Collateral	$ 151,265	$ 86,409
Weighted Average Borrowing Rate	3.40%	2.30%