v3.26.3
Condensed Statements of Changes in Net Assets (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Investment Company, Net Assets [Roll Forward]        
Beginning balance $ 5,224,553 $ 2,014,693 $ 3,485,248 $ 100
Proceeds from Units Issued 817,474 603,377 2,182,198 2,617,692
Net Investment Income (Loss) 46,626 20,159 118,474 41,224
Distribution Reinvested 19,954 8,460 51,725 11,514
Distributions (47,066) (20,612) (119,768) (42,190)
Net Change in Unrealized Gain (Loss) on Investment in the Aggregator 279,047 63,835 660,204 109,338
Servicing Fees (14,136) (14,069) (40,429) (61,637)
Conversion of Units Between Classes or Series 0 0 0 0
Redemption of Units, Net of Early Redemption Deduction (5,322)   (16,522) (198)
Ending balance 6,321,130 2,675,843 6,321,130 2,675,843
Series I Units        
Investment Company, Net Assets [Roll Forward]        
Beginning balance [1] 3,518,013 1,288,817 2,289,703 100
Proceeds from Units Issued [1] 586,629 376,191 1,556,438 1,635,069
Net Investment Income (Loss) [1] 31,337 12,594 78,636 25,691
Distribution Reinvested [1] 8,810 3,232 21,945 4,369
Distributions [1] (31,496) (12,853) (79,183) (26,255)
Net Change in Unrealized Gain (Loss) on Investment in the Aggregator [1] 186,153 40,229 436,170 68,591
Conversion of Units Between Classes or Series [1] 18,857   21,164 771
Redemption of Units, Net of Early Redemption Deduction [1] (2,013)   (8,583) (126)
Ending balance [1] 4,316,290 1,708,210 4,316,290 1,708,210
Series II Units        
Investment Company, Net Assets [Roll Forward]        
Beginning balance [1] 0 0 0 0
Proceeds from Units Issued [1] 30,000   30,000  
Net Investment Income (Loss) [1] 228   228  
Distributions [1] (229)   (229)  
Net Change in Unrealized Gain (Loss) on Investment in the Aggregator [1] 1,430   1,430  
Redemption of Units, Net of Early Redemption Deduction [1] 1   1  
Ending balance [1] 31,430 0 31,430 0
Series III Units        
Investment Company, Net Assets [Roll Forward]        
Beginning balance [1] 0 0 0 0
Ending balance [1] 0 0 0 0
Class S Units        
Investment Company, Net Assets [Roll Forward]        
Beginning balance 1,520,075 673,373 1,080,003 0
Proceeds from Units Issued 191,656 202,186 526,410 905,532
Net Investment Income (Loss) 13,544 6,898 35,568 14,291
Distribution Reinvested 9,828 4,816 26,450 6,554
Distributions (13,810) (7,079) (36,271) (14,665)
Net Change in Unrealized Gain (Loss) on Investment in the Aggregator 82,121 21,663 200,588 37,546
Servicing Fees (13,886) (13,366) (38,939) (59,924)
Conversion of Units Between Classes or Series (18,857) (9,616) (21,326) (10,387)
Redemption of Units, Net of Early Redemption Deduction (3,317)   (5,129) (72)
Ending balance 1,767,354 878,875 1,767,354 878,875
Class D Units        
Investment Company, Net Assets [Roll Forward]        
Beginning balance 186,215 52,253 115,292 0
Proceeds from Units Issued 9,189 25,000 69,350 76,841
Net Investment Income (Loss) 1,517 667 4,042 1,242
Distribution Reinvested 1,316 412 3,330 591
Distributions (1,531) (680) (4,085) (1,270)
Net Change in Unrealized Gain (Loss) on Investment in the Aggregator 9,343 1,943 22,016 3,201
Servicing Fees (250) (703) (1,490) (1,713)
Conversion of Units Between Classes or Series   9,616 162 9,616
Redemption of Units, Net of Early Redemption Deduction 7   (2,811)  
Ending balance 205,806 88,508 205,806 88,508
General Partner Interest        
Investment Company, Net Assets [Roll Forward]        
Beginning balance 250 250 250 0
Proceeds from Units Issued [2]       250
Ending balance $ 250 $ 250 $ 250 $ 250
[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.
[2] The General Partner did not receive any Units for its General Partner Interest contribution to BXINFRA U.S