v3.25.3

Asset-Specific Debt, Net (Detail) $ in Thousands	9 Months Ended	12 Months Ended
Asset-Specific Debt, Net (Detail) $ in Thousands	Sep. 30, 2025 USD ($) loan	Dec. 31, 2024 USD ($) loan
Debt Instrument [Line Items]
Debt instrument, variable interest rate, type [Extensible Enumeration]	SOFR	SOFR
Asset-specific debt, net
Debt Instrument [Line Items]
Count, financing provided \| loan	3	2
Count, collateral assets \| loan	3	2
Principal balance	$ 629,890	$ 1,228,110
Principal Balance, collateral assets	781,189	1,467,185
Book Value	627,916	1,224,841
Book Value, collateral assets	$ 775,248	$ 1,459,864
Wtd. Avg. Yield/Cost, financing provided	3.18%	3.20%
Wtd. Avg. Yield/Cost, collateral assets	4.52%	4.03%

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BLACKSTONE MORTGAGE TRUST, INC. 10-Q