Transactions With Related Parties - Affiliate Transactions (Details) $ in Thousands, € in Millions, £ in Millions	3 Months Ended					12 Months Ended
	Dec. 31, 2024 USD ($) loan	Sep. 30, 2024 EUR (€)	Sep. 30, 2024 GBP (£)	Jun. 30, 2024 GBP (£)	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2024 GBP (£)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 EUR (€)	Sep. 30, 2024 GBP (£)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 EUR (€)	Dec. 31, 2019 EUR (€)	Mar. 31, 2019 GBP (£)	Dec. 31, 2018 GBP (£)
Related Party Transaction [Line Items]
Origination and other fees received on loans receivable						$ 31,693	$ 17,992	$ 74,930
Face amount of loans	$ 19,203,126					19,203,126
Repayment of loan participations						235,960	0	0
Principal collections, sales proceeds, and cost-recovery proceeds from loans receivable and debt securities						4,790,510	$ 2,840,467	$ 3,254,595
Related Party
Related Party Transaction [Line Items]
Face amount of loans									£ 490.0	$ 94,400		£ 303.5		€ 350.0	€ 350.0	£ 240.1	£ 148.7
Related party transaction, interest in loan, percentage		17.00%	17.00%
Selling loan amount | €		€ 232.0
Remaining loan amount in new lenders | €											€ 347.0
Repayment of loan participations | £			£ 46.4
Principal collections, sales proceeds, and cost-recovery proceeds from loans receivable and debt securities					$ 98,600
Related Party | Senior Loans
Related Party Transaction [Line Items]
Face amount of loans										$ 560,000
Related Party | Senior Participations
Related Party Transaction [Line Items]
Repayment of loan participations | £				£ 186.0
Proceeds of loan participations | £			£ 100.0
Related Party | Junior Loan Participation
Related Party Transaction [Line Items]
Repayment of loan participations | £				£ 46.5
Secured term loans, net
Related Party Transaction [Line Items]
Face Value	1,764,437					1,764,437
B-5 Term Loan | Secured term loans, net
Related Party Transaction [Line Items]
Face Value	650,000					650,000
December 2024 | Senior Secured Notes [Member]
Related Party Transaction [Line Items]
Face Value	450,000					450,000
B-4 Term Loan | Secured term loans, net
Related Party Transaction [Line Items]
Face Value	805,169					805,169
Blackstone-Advised Investment Vehicles, or the Funds | B-5 Term Loan | Secured term loans, net | Related Party
Related Party Transaction [Line Items]
Face Value	62,500					62,500
Blackstone-Advised Investment Vehicles, or the Funds | December 2024 | Senior Secured Notes [Member] | Related Party
Related Party Transaction [Line Items]
Face Value	$ 80,000					$ 80,000
Blackstone-Advised Investment Vehicles, or the Funds | B-4 Term Loan | Related Party
Related Party Transaction [Line Items]
Percentage of total secured term loans								4.00%					4.00%
Blackstone-Advised Investment Vehicles, or the Funds | B-4 Term Loan | Secured term loans, net | Related Party
Related Party Transaction [Line Items]
Face Value								$ 33,000					$ 33,000
Agency Multifamily Lending Partnership | Related Party
Related Party Transaction [Line Items]
Number of loans referred | loan	3
Origination and other fees received on loans receivable	$ 217