v3.26.3
Investments and Fair Value Measurement - Schedule of Quantitative Inputs and Assumptions used for Valuation of Investments (Details)
$ in Thousands
Sep. 30, 2026
USD ($)
Dec. 31, 2025
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 6,421,142 $ 3,555,635
BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total Assets 7,194,577 4,224,958
BXINFRA Aggregator (CYM) L.P. | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 3,822,704 2,248,586
Total Assets 3,822,704 3,025,154
Equity Investments | WACC | Discounted Cash Flow | BXINFRA Aggregator (CYM) L.P. | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 3,242,883 $ 2,041,413
Equity Investments | WACC | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.078 0.087
Equity Investments | WACC | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.142 0.119
Equity Investments | WACC | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.102 0.104
Equity Investments | WACC | Transaction Price | BXINFRA Aggregator (CYM) L.P. | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 328,548  
Equity Investments | Exit Capitalization | Discounted Cash Flow | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   6.1
Equity Investments | Exit Capitalization | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.061  
Equity Investments | Exit Capitalization | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.074  
Equity Investments | Exit Capitalization | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.066 0.061
Equity Investments | Exit Multiple | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 11.5 11.5
Equity Investments | Exit Multiple | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 20.0 20.4
Equity Investments | Exit Multiple | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 17.8 17.7
Equity Investments | Measurement Input, Discount Rate | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.128  
Equity Investments | Measurement Input, Discount Rate | Yield Analysis | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.077  
Debt Investments | Discounted Cash Flow | BXINFRA Aggregator (CYM) L.P. | Debt Investments - Infrastructure | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 128,440  
Debt Investments | Transaction Price | BXINFRA Aggregator (CYM) L.P. | Debt Investments - Infrastructure | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 25,942  
Debt Investments | Third Party Pricing | BXINFRA Aggregator (CYM) L.P. | Debt Investments - Infrastructure | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 87,553 $ 207,173
Debt Investments | Third Party Pricing | BXINFRA Aggregator (CYM) L.P. | Debt Investments - Liquids | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 9,338  
Debt Investments | Measurement Input, Discount Rate | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs 0.067  
Affiliated Investee Funds | WACC | Discounted Cash Flow | BXINFRA Aggregator (CYM) L.P. | Level III    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments in Affiliated Investee Funds   $ 776,568
Affiliated Investee Funds | WACC | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.054
Affiliated Investee Funds | WACC | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.214
Affiliated Investee Funds | WACC | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.100
Affiliated Investee Funds | Exit Capitalization | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.046
Affiliated Investee Funds | Exit Capitalization | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.072
Affiliated Investee Funds | Exit Capitalization | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.062
Affiliated Investee Funds | Exit Multiple | Discounted Cash Flow | Minimum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   11.5
Affiliated Investee Funds | Exit Multiple | Discounted Cash Flow | Maximum | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   24.7
Affiliated Investee Funds | Exit Multiple | Discounted Cash Flow | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   14.8
Affiliated Investee Funds | Input Discount To Sale | Other | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   30.1
Affiliated Investee Funds | Input Discount To Sale | Other | Weighted-Average | BXINFRA Aggregator (CYM) L.P.    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement inputs   0.301