Fair Value - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Financial Assets:
Available-for-sale securities	$ 91,941	$ 93,806
Domestic servicing rights	23,143	22,390
Derivative assets	84,972	175,520
VIE assets	62,163,347	62,556,497
Financial Liabilities:
Derivative liabilities	72,975	94,890
VIE liabilities	55,006,596	55,363,025
Primary Beneficiary
Financial Assets:
Woodstar Fund investments	2,065,498	2,073,533
VIE assets	63,800
Financial Liabilities:
VIE liabilities	100
Fair value measurements on recurring basis
Financial Assets:
Equity security	3,800	5,146
Derivative assets	84,972	175,520
Total	42,217,907	43,851,324
Financial Liabilities:
Derivative liabilities	72,975	94,890
Total	35,974,060	37,383,435
Fair value measurements on recurring basis | Loans under fair value option
Financial Assets:
Loans under fair value option	2,446,636	2,516,008
Fair value measurements on recurring basis | RMBS
Financial Assets:
Available-for-sale securities	91,941	93,806
Fair value measurements on recurring basis | CMBS
Financial Assets:
Available-for-sale securities	31,299	27,345
Fair value measurements on recurring basis | Woodstar Fund investments
Financial Assets:
Woodstar Fund investments	2,065,498	2,073,533
Fair value measurements on recurring basis | Domestic servicing rights
Financial Assets:
Domestic servicing rights	23,143	22,390
Fair value measurements on recurring basis | VIE assets | Primary Beneficiary
Financial Assets:
VIE assets	37,470,618	38,937,576
Fair value measurements on recurring basis | VIE liabilities | Primary Beneficiary
Financial Liabilities:
VIE liabilities	35,901,085	37,288,545
Fair value measurements on recurring basis | Level I
Financial Assets:
Equity security	3,800	5,146
Derivative assets	0	0
Total	3,800	5,146
Financial Liabilities:
Derivative liabilities	0	0
Total	0	0
Fair value measurements on recurring basis | Level I | Loans under fair value option
Financial Assets:
Loans under fair value option	0	0
Fair value measurements on recurring basis | Level I | RMBS
Financial Assets:
Available-for-sale securities	0	0
Fair value measurements on recurring basis | Level I | CMBS
Financial Assets:
Available-for-sale securities	0	0
Fair value measurements on recurring basis | Level I | Woodstar Fund investments
Financial Assets:
Woodstar Fund investments	0	0
Fair value measurements on recurring basis | Level I | Domestic servicing rights
Financial Assets:
Domestic servicing rights	0	0
Fair value measurements on recurring basis | Level I | VIE assets | Primary Beneficiary
Financial Assets:
VIE assets	0	0
Fair value measurements on recurring basis | Level I | VIE liabilities | Primary Beneficiary
Financial Liabilities:
VIE liabilities	0	0
Fair value measurements on recurring basis | Level II
Financial Assets:
Equity security	0	0
Derivative assets	84,972	175,520
Total	89,000	175,520
Financial Liabilities:
Derivative liabilities	72,975	94,890
Total	31,992,436	31,869,283
Fair value measurements on recurring basis | Level II | Loans under fair value option
Financial Assets:
Loans under fair value option	0	0
Fair value measurements on recurring basis | Level II | RMBS
Financial Assets:
Available-for-sale securities	0	0
Fair value measurements on recurring basis | Level II | CMBS
Financial Assets:
Available-for-sale securities	4,028	0
Fair value measurements on recurring basis | Level II | Woodstar Fund investments
Financial Assets:
Woodstar Fund investments	0	0
Fair value measurements on recurring basis | Level II | Domestic servicing rights
Financial Assets:
Domestic servicing rights	0	0
Fair value measurements on recurring basis | Level II | VIE assets | Primary Beneficiary
Financial Assets:
VIE assets	0	0
Fair value measurements on recurring basis | Level II | VIE liabilities | Primary Beneficiary
Financial Liabilities:
VIE liabilities	31,919,461	31,774,393
Fair value measurements on recurring basis | Level III
Financial Assets:
Equity security	0	0
Derivative assets	0	0
Total	42,125,107	43,670,658
Financial Liabilities:
Derivative liabilities	0	0
Total	3,981,624	5,514,152
Fair value measurements on recurring basis | Level III | Loans under fair value option
Financial Assets:
Loans under fair value option	2,446,636	2,516,008
Fair value measurements on recurring basis | Level III | RMBS
Financial Assets:
Available-for-sale securities	91,941	93,806
Fair value measurements on recurring basis | Level III | CMBS
Financial Assets:
Available-for-sale securities	27,271	27,345
Fair value measurements on recurring basis | Level III | Woodstar Fund investments
Financial Assets:
Woodstar Fund investments	2,065,498	2,073,533
Fair value measurements on recurring basis | Level III | Domestic servicing rights
Financial Assets:
Domestic servicing rights	23,143	22,390
Fair value measurements on recurring basis | Level III | VIE assets | Primary Beneficiary
Financial Assets:
VIE assets	37,470,618	38,937,576
Fair value measurements on recurring basis | Level III | VIE liabilities | Primary Beneficiary
Financial Liabilities:
VIE liabilities	$ 3,981,624	$ 5,514,152