v3.26.3
Related Party Transactions (Detail)
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2026
USD ($)
limited_partnership_unit
loan
Sep. 30, 2025
USD ($)
limited_partnership_unit
loan
Sep. 30, 2026
USD ($)
loan
limited_partnership_unit
shares
Sep. 30, 2025
USD ($)
loan
limited_partnership_unit
Dec. 31, 2025
USD ($)
Related Party Transaction [Line Items]          
Performance participation allocation     $ 112,500,000    
Gross management fee     48,100,000    
Administration fee payable     3,800,000    
Payment for servicing fees     $ 9,081,000 $ 2,990,000  
Series I Units          
Related Party Transaction [Line Items]          
Shares received for equity (in shares) | shares     180,705    
Blackstone Infrastructure Strategies (TE) L.P.          
Related Party Transaction [Line Items]          
Payment for servicing fees     $ 3,692,000 1,105,000  
BXINFRA Aggregator (CYM) L.P.          
Related Party Transaction [Line Items]          
Performance participation allocation     119,100,000    
Cash paid for performance participation allocation     70,400,000    
Management Fees $ 20,345,000 $ 8,597,000 50,961,000 19,298,000  
Accrued administration fees 300,100,000 120,300,000 406,000,000.0 578,200,000  
BXINFRA Aggregator (CYM) L.P. | Related Party | BXINFRA Warehouse          
Related Party Transaction [Line Items]          
Related party transaction, amounts of transaction 320,000,000.0 $ 258,500,000 630,000,000.0 $ 2,300,000,000  
BXPE US Aggregator (CYM) L.P          
Related Party Transaction [Line Items]          
Number of cross-transactions | limited_partnership_unit   5   5  
Related Party          
Related Party Transaction [Line Items]          
Performance participation allocation 47,200,000 $ 12,300,000   $ 22,700,000  
Gross management fee 19,300,000 7,900,000   17,800,000  
Management fee waived       9,900,000  
Administration fee payable 1,500,000 600,000   1,400,000  
Payment for servicing fees 3,600,000 1,600,000 $ 9,100,000 3,000,000.0  
Related Party | Performance Participation Allocation Received          
Related Party Transaction [Line Items]          
Related party transaction, amounts of transaction         $ 5,000,000.0
Related Party | Class S Units          
Related Party Transaction [Line Items]          
Management and service fees, rate     0.85%    
Related Party | Class D Units          
Related Party Transaction [Line Items]          
Management and service fees, rate     0.25%    
Related Party | Blackstone Infrastructure Strategies (TE) L.P.          
Related Party Transaction [Line Items]          
Performance participation allocation 13,200,000 3,300,000 $ 31,600,000 6,100,000  
Gross management fee 5,400,000 2,100,000 13,500,000 4,800,000  
Administration fee payable 600,000 200,000 1,500,000 400,000  
Payment for servicing fees (1,500,000) (600,000) $ (3,700,000) (1,100,000)  
Related Party | Blackstone Infrastructure Strategies (TE) L.P. | Class S Units          
Related Party Transaction [Line Items]          
Management and service fees, rate     0.85%    
Related Party | Blackstone Infrastructure Strategies (TE) L.P. | Class D Units          
Related Party Transaction [Line Items]          
Management and service fees, rate     0.25%    
Related Party | BXINFRA Aggregator (CYM) L.P.          
Related Party Transaction [Line Items]          
Performance participation allocation 49,800,000 13,400,000   24,500,000  
Cash paid for performance participation allocation 29,200,000        
Management Fees 20,300,000 8,600,000   19,300,000  
Investment company, voluntary fee waived   0   10,700,000  
Aggregator transactional NAV     0.10%    
Accrued administration fees 1,600,000 700,000 $ 4,100,000 1,500,000  
Investments in affiliated investee funds 2,100,000,000   2,100,000,000   $ 920,500,000
Specified expenses as a percentage of net asset value maximum         0.50%
Accrued waived expenses   0   700,000  
Investment company cash received $ 21,900,000 $ 14,800,000 $ 32,100,000 $ 19,000,000.0  
Aggregator acquired number of loans | loan 0 0 3 0  
Aggregate investment credit amount extended     $ 11,600,000    
Related Party | BXINFRA Aggregator (CYM) L.P. | BXINFRA Warehouse          
Related Party Transaction [Line Items]          
Number of new investments | limited_partnership_unit   0   4  
Investment company cash received       $ 67,100,000  
Related Party | BXINFRA Aggregator (CYM) L.P. | BXINFRA Warehouse | Extension Of Credit          
Related Party Transaction [Line Items]          
Number of new investments | limited_partnership_unit 2   2    
Investment company cash received $ 34,000,000.0   $ 34,000,000.0    
Related Party | BXINFRA Aggregator (CYM) L.P. | BXINFRA Warehouse | Follow On Extensions          
Related Party Transaction [Line Items]          
Number of new investments | limited_partnership_unit     2    
Investment company cash received 3,700,000   $ 18,100,000    
Related Party | BXINFRA Aggregator (CYM) L.P. | Performance Participation Allocation | General Partner          
Related Party Transaction [Line Items]          
Percentage of performance participation allocation of partners to total return     12.50%    
Percentage of annual hurdle amount     5.00%    
Percentage of high water mark catch up     100.00%    
Written notice period     60 days    
Related Party | BXINFRA Aggregator (CYM) L.P. | Series I Units          
Related Party Transaction [Line Items]          
Shares received for equity (in shares) | shares     180,705    
Related Party | BXINFRA Aggregator (CYM) L.P. | Performance Participation Allocation Received          
Related Party Transaction [Line Items]          
Related party transaction, amounts of transaction         $ 5,000,000.0
Related Party | BXINFRA Aggregator (CYM) L.P. | Investment Manager | Partnership Agreement and Investment Management Agreement          
Related Party Transaction [Line Items]          
Percentage of administration fee payable     0.10%    
Related Party | BXINFRA Aggregator (CYM) L.P. | Series I Units | Investment Manager          
Related Party Transaction [Line Items]          
Percentage of management fee payable     1.25%    
Related Party | BXINFRA Aggregator (CYM) L.P. | Series II Units | Investment Manager          
Related Party Transaction [Line Items]          
Percentage of management fee payable     1.05%    
Related Party | BXINFRA Aggregator (CYM) L.P. | Series III Units | Investment Manager          
Related Party Transaction [Line Items]          
Percentage of management fee payable     0.95%    
Related Party | BXINFRA U.S. | Series I Units          
Related Party Transaction [Line Items]          
Shares received for equity (in shares) | shares     180,640    
Related Party | BXPE US Aggregator (CYM) L.P          
Related Party Transaction [Line Items]          
Aggregate investment credit amount extended $ 0 $ 7,000,000.0 $ 0 $ 7,000,000.0