Secured Financing Agreements - Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets Sold under Agreements to Repurchase [Line Items]
Principal	$ 3,228,748	$ 2,432,115
Repurchase Agreements
Assets Sold under Agreements to Repurchase [Line Items]
Principal	3,235,072	2,444,091
Repurchase Agreements | Overnight
Assets Sold under Agreements to Repurchase [Line Items]
Principal	282,250	0
Repurchase Agreements | 1 to 29 days
Assets Sold under Agreements to Repurchase [Line Items]
Principal	774,901	272,490
Repurchase Agreements | 30 to 59 days
Assets Sold under Agreements to Repurchase [Line Items]
Principal	216,357	495,636
Repurchase Agreements | 60 to 89 days
Assets Sold under Agreements to Repurchase [Line Items]
Principal	322,328	305,426
Repurchase Agreements | 90 to 119 days
Assets Sold under Agreements to Repurchase [Line Items]
Principal	69,445	54,376
Repurchase Agreements | 120 to 180 days
Assets Sold under Agreements to Repurchase [Line Items]
Principal	777,682	105,727
Repurchase Agreements | 180 days to 1 year
Assets Sold under Agreements to Repurchase [Line Items]
Principal	205,604	39,620
Repurchase Agreements | 1 to 2 years
Assets Sold under Agreements to Repurchase [Line Items]
Principal	241,397	808,601
Repurchase Agreements | 2 to 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Principal	0	0
Repurchase Agreements | Greater than 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Principal	$ 345,108	$ 362,215
Repurchase Agreements | Weighted Average Borrowing Rates
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.70%	7.51%
Repurchase Agreements | Weighted Average Borrowing Rates | Overnight
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.47%
Repurchase Agreements | Weighted Average Borrowing Rates | 1 to 29 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.99%	7.35%
Repurchase Agreements | Weighted Average Borrowing Rates | 30 to 59 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.80%	6.68%
Repurchase Agreements | Weighted Average Borrowing Rates | 60 to 89 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.34%	7.17%
Repurchase Agreements | Weighted Average Borrowing Rates | 90 to 119 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.27%	7.46%
Repurchase Agreements | Weighted Average Borrowing Rates | 120 to 180 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	8.47%	7.09%
Repurchase Agreements | Weighted Average Borrowing Rates | 180 days to 1 year
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.26%	7.06%
Repurchase Agreements | Weighted Average Borrowing Rates | 1 to 2 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.93%	9.36%
Repurchase Agreements | Weighted Average Borrowing Rates | 2 to 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	0.00%	0.00%
Repurchase Agreements | Weighted Average Borrowing Rates | Greater than 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.07%	5.11%
Repurchase Agreements | Minimum | Overnight
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.45%
Repurchase Agreements | Minimum | 1 to 29 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.20%	6.30%
Repurchase Agreements | Minimum | 30 to 59 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.00%	5.58%
Repurchase Agreements | Minimum | 60 to 89 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.46%	5.93%
Repurchase Agreements | Minimum | 90 to 119 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.27%	6.59%
Repurchase Agreements | Minimum | 120 to 180 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.72%	6.72%
Repurchase Agreements | Minimum | 180 days to 1 year
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.18%	6.66%
Repurchase Agreements | Minimum | 1 to 2 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.93%	8.36%
Repurchase Agreements | Minimum | Greater than 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.07%	5.10%
Repurchase Agreements | Maximum | Overnight
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.55%
Repurchase Agreements | Maximum | 1 to 29 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.78%	8.22%
Repurchase Agreements | Maximum | 30 to 59 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.76%	7.87%
Repurchase Agreements | Maximum | 60 to 89 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.10%	7.85%
Repurchase Agreements | Maximum | 90 to 119 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.27%	7.80%
Repurchase Agreements | Maximum | 120 to 180 days
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	12.50%	7.80%
Repurchase Agreements | Maximum | 180 days to 1 year
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	6.83%	7.39%
Repurchase Agreements | Maximum | 1 to 2 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	7.93%	12.50%
Repurchase Agreements | Maximum | Greater than 3 years
Assets Sold under Agreements to Repurchase [Line Items]
Borrowing rates (as a percent)	5.07%	7.15%