Secured Debt Arrangements, Net - Summary of Outstanding Balances, Maximum and Average Balances of Borrowings (Details) $ in Thousands, € in Millions, £ in Millions, kr in Billions	9 Months Ended	12 Months Ended
	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2025 GBP (£)	Sep. 30, 2025 EUR (€)	Sep. 30, 2025 SEK (kr)	Dec. 31, 2024 GBP (£)	Dec. 31, 2024 EUR (€)	Dec. 31, 2024 SEK (kr)
Line of Credit
Line of Credit Facility [Line Items]
Balance	$ 5,896,015	$ 4,814,973
Collateral	8,064,105	7,032,800
Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	0	0
JPMorgan \| Line of Credit
Line of Credit Facility [Line Items]
Balance	1,713,891	1,033,504
Collateral	2,375,092	1,832,859
Maximum Month-End Balance	1,713,890	1,063,261
Average Month-End Balance	1,515,568	969,759
JPMorgan \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	1,713,891	1,033,504
Morgan Stanley Facility \| USD
Line of Credit Facility [Line Items]
Balance	365,256
Collateral	483,527
Maximum Month-End Balance	365,256
Average Month-End Balance	306,119
Morgan Stanley Facility \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	299,453
Collateral	368,600
Maximum Month-End Balance	300,726
Average Month-End Balance	207,836
Morgan Stanley Facility \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	365,256	0
Morgan Stanley Facility \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	299,453	0
DB \| Line of Credit
Line of Credit Facility [Line Items]
Balance	27,300	123,434
Collateral	45,500	199,217
Maximum Month-End Balance	27,300	278,703
Average Month-End Balance	68,967	201,020
DB \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	27,300	123,434
Goldman \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance		0
Collateral		0
Maximum Month-End Balance		11,620
Average Month-End Balance		2,903
Goldman \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	440,245	373,706
Collateral	570,147	485,054
Maximum Month-End Balance	440,244	390,163
Average Month-End Balance	416,849	251,571
CS Facility \| Line of Credit
Line of Credit Facility [Line Items]
Balance	498,105	462,886
Collateral	751,904	702,927
Maximum Month-End Balance	505,776	758,201
Average Month-End Balance	516,416	640,453
CS Facility \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	498,105	462,886
CS Facility \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	281,612
Collateral	410,332
Maximum Month-End Balance	293,685
Average Month-End Balance	63,922
CS Facility \| Line of Credit \| Fx contracts - EUR
Line of Credit Facility [Line Items]
Balance	281,612
HSBC Facility \| Line of Credit
Line of Credit Facility [Line Items]
Balance	0	627,646
Collateral	0	839,123
Maximum Month-End Balance	674,118	672,422
Average Month-End Balance	514,882	653,182
HSBC Facility \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	0	377,483
HSBC Facility \| Line of Credit \| Fx contracts - EUR
Line of Credit Facility [Line Items]
Balance	0	250,162
Barclays Facility \| Line of Credit
Line of Credit Facility [Line Items]
Balance		321,546
Collateral		420,774
Maximum Month-End Balance		353,153
Average Month-End Balance		242,792
Barclays Facility \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	475,291	321,546
Collateral	652,029
Maximum Month-End Balance	475,291
Average Month-End Balance	334,338
Barclays Facility \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	124,282	0
Collateral	157,263
Maximum Month-End Balance	124,817
Average Month-End Balance	124,283
MUFG Facility \| Line of Credit
Line of Credit Facility [Line Items]
Balance		171,972
Collateral		209,493
Maximum Month-End Balance		211,057
Average Month-End Balance		197,420
MUFG Facility \| Line of Credit \| Fx contracts - GBP
Line of Credit Facility [Line Items]
Balance	0	171,972
Churchill \| Line of Credit
Line of Credit Facility [Line Items]
Balance		121,289
Churchill \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	0	121,289
Santander Facility \| Line of Credit \| USD
Line of Credit Facility [Line Items]
Balance	0	0
Collateral		0
Maximum Month-End Balance		67,500
Average Month-End Balance		56,250
Santander Facility \| Line of Credit \| Fx contracts - EUR
Line of Credit Facility [Line Items]
Balance		0
Collateral		0
Maximum Month-End Balance		54,677
Average Month-End Balance		22,684
Barclays Securitization \| Line of Credit
Line of Credit Facility [Line Items]
Balance	1,680,125	1,587,779	£ 800.3	€ 335.2	kr 2.0	£ 716.8	€ 493.9	kr 2.0
Collateral	2,249,711	2,182,088
Maximum Month-End Balance	1,801,532	2,249,538
Average Month-End Balance	1,720,970	2,041,421
Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Balance	0	0
Collateral	0	0
Maximum Month-End Balance	0	150,000
Average Month-End Balance	19,625	38,796
Churchill Facility \| Line of Credit
Line of Credit Facility [Line Items]
Collateral		161,264
Maximum Month-End Balance		126,080
Average Month-End Balance		123,684
JP Morgan Chase, DB Repurchase Facility, Goldman Sachs, Credit Suisse, Barclays Facility, HSBC Facilities And Barclays Securitization \| Line of Credit
Line of Credit Facility [Line Items]
Balance	$ 5,905,560	$ 4,823,762