v3.26.3
Condensed Consolidated Statements of Assets and Liabilities (Unaudited) (Parenthetical) - BXINFRA Aggregator (CYM) L.P - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2026
Dec. 31, 2025
Investment owned, cost $ 5,529,843,000 $ 3,324,540
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration] Affiliated Entity [Member] Affiliated Entity [Member]
Other Liability, Related Party [Extensible Enumeration] Affiliated Entity [Member] Affiliated Entity [Member]
Units outstanding (in shares) 205,439,267 129,371,828
Series I Units    
Units issued (in shares) [1] 137,502,712 83,138,103
Units outstanding (in shares) [1] 137,502,712 83,138,103
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
Series II Units    
Units issued (in shares) [1] 1,000,293 0
Units outstanding (in shares) [1] 1,000,293 0
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
Series III Units    
Units issued (in shares) [1] 0 0
Units outstanding (in shares) [1] 0 0
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
BXINFRA Aggregator (CYM) L.P.    
Investment owned, cost $ 4,264,369,000 $ 3,019,921,000
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration] Affiliated Entity [Member] Affiliated Entity [Member]
Derivative assets at cost $ 0 $ 0
Derivative liabilities at cost $ 0 $ 0
Units outstanding (in shares) 215,497,386 138,551,291
BXINFRA Aggregator (CYM) L.P. | Series I Units    
Units issued (in shares) 214,497,433 138,551,291
Units outstanding (in shares) 214,497,433 138,551,291
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
BXINFRA Aggregator (CYM) L.P. | Series II Units    
Units issued (in shares) 999,953 0
Units outstanding (in shares) 999,953 0
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
BXINFRA Aggregator (CYM) L.P. | Series III Units    
Units issued (in shares) 0 0
Units outstanding (in shares) 0 0
Common Stock, Shares Authorized, Unlimited [Fixed List] Unlimited Unlimited
BXINFRA Aggregator (CYM) L.P. | Investment, Affiliated Issuer    
Investment owned, cost $ 1,543,213,000 $ 802,546,000
[1] On March 6, 2026, BXINFRA U.S. redesignated existing Class I Units as Class I-Series I Units and designated two new series of Class I Units, Class I-Series II Units and Class I-Series III Units.