v3.25.4
Related Party Transactions - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 5 Months Ended 12 Months Ended
Sep. 30, 2025
Dec. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Related Party Transaction [Line Items]        
Performance participation allocation $ 44,100     $ 0
Gross Management Fee     $ 28,300 0
Administration fee payable     2,300 0
Servicing Fees Payable   $ 0 69,167 0
Investment company, management fee, voluntary fee waived     9,900  
BXINFRA Aggregator (CYM) L.P. [Member]        
Related Party Transaction [Line Items]        
Performance participation allocation     47,400 0
Management fee expense   $ 0 30,519 0
Investment company, voluntary fee waived     $ 10,700  
Specified expenses as a percentage of net asset value maximum     0.50%  
Accrued administration fees     $ 2,400 0
Accrued waived expenses     700 $ 0
Investment company, committed capital     589,200  
Investments In Affliated Investee Funds     $ 920,500  
Aggregator Transactional NAV     0.10%  
Cash distributions received from investment funds     $ 22,000  
BXINFRA Aggregator (CYM) L.P. [Member] | BXINFRA Warehouse [Member]        
Related Party Transaction [Line Items]        
Related party transaction, amounts of transaction     2,300,000  
BXINFRA Aggregator (CYM) L.P. [Member] | Five investments [Member]        
Related Party Transaction [Line Items]        
Related party transaction, amounts of transaction     159,500  
BXINFRA Aggregator (CYM) L.P. [Member] | One Cross transaction [Member]        
Related Party Transaction [Line Items]        
Related party transaction, amounts of transaction     $ 2,500  
Class S Units [Member]        
Related Party Transaction [Line Items]        
Management and service fees, rate     0.85%  
Class D Units [Member]        
Related Party Transaction [Line Items]        
Management and service fees, rate     0.25%  
Investment Manager [Member] | BXINFRA Aggregator (CYM) L.P. [Member]        
Related Party Transaction [Line Items]        
Percentage of management fee payable     1.25%  
Performance Participation Allocation [Member] | BXINFRA Aggregator (CYM) L.P. [Member]        
Related Party Transaction [Line Items]        
Percentage of annual hurdle amount     5.00%  
Partnership Agreement and Investment Management Agreement [Member] | Investment Manager [Member] | BXINFRA Aggregator (CYM) L.P. [Member]        
Related Party Transaction [Line Items]        
Percentage of administration fee payable     0.10%  
General Partner [Member] | Performance Participation Allocation [Member] | BXINFRA Warehouse [Member]        
Related Party Transaction [Line Items]        
Percentage of performance participation allocation of partners to total return     12.50%  
General Partner [Member] | Performance Participation Allocation [Member] | BXINFRA Aggregator (CYM) L.P. [Member]        
Related Party Transaction [Line Items]        
Percentage Of high water mark catch Up     100.00%