v3.25.4
Investments and Fair Value Measurement - Summary of Fair Value Measurement Inputs and Valuation Techniques (Detail)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 3,555,635 $ 0
BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment, Type [Extensible Enumeration] Infrastructure Debt Investment [Member]  
Debt Investments [Member] | Valuation Technique Transactional Value [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Transaction Price  
Debt Investments [Member] | Valuation Technique Third Party Pricing [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Third-Party Pricing  
Debt Investments [Member] | Valuation Technique Other [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Other  
Equity Investments [Member] | Valuation Technique Transactional Value [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Transaction Price  
Equity Investments [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Discounted Cash Flows  
Unobservable Inputs WACC  
Equity Investments [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.087  
Equity Investments [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.119  
Equity Investments [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.104  
Equity Investments [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unobservable Inputs Exit Capitalization Rate  
Measurement Input 0.061  
Equity Investments [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.061  
Equity Investments [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unobservable Inputs Exit Multiple  
Equity Investments [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.115  
Equity Investments [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.204  
Equity Investments [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.177  
Equity Investments [Member] | Lower Impact [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Lower  
Equity Investments [Member] | Lower Impact [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Lower  
Equity Investments [Member] | Higher Impact [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Higher  
Investments in Affiliated Investee Funds [Member] | Valuation Technique Transactional Value [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Transaction Price  
Investments in Affiliated Investee Funds [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Discounted Cash Flows  
Unobservable Inputs WACC  
Investments in Affiliated Investee Funds [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.054  
Investments in Affiliated Investee Funds [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.214  
Investments in Affiliated Investee Funds [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.10  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unobservable Inputs Exit Capitalization Rate  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.046  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.072  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.062  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unobservable Inputs Exit Multiple  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.115  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.247  
Investments in Affiliated Investee Funds [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Measurement Input 0.148  
Investments in Affiliated Investee Funds [Member] | Measurement Input Discount To Sale [Member] | Valuation Technique Other [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Valuation Techniques Other  
Unobservable Inputs Discount toEscrow  
Measurement Input 0.301  
Investments in Affiliated Investee Funds [Member] | Lower Impact [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Lower  
Investments in Affiliated Investee Funds [Member] | Lower Impact [Member] | Measurement Input Exit Capitalization [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Lower  
Investments in Affiliated Investee Funds [Member] | Higher Impact [Member] | Measurement Input Exit Multiple [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Higher  
Investments in Affiliated Investee Funds [Member] | Higher Impact [Member] | Measurement Input Discount To Sale [Member] | Valuation Technique Other [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Impact to Valuation from an Increase in Input Higher  
Fair Value, Inputs, Level 3 [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 3,025,154  
Investments in Affiliated Investee Funds 2,248,586  
Fair Value, Inputs, Level 3 [Member] | Debt Investments [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 207,173  
Fair Value, Inputs, Level 3 [Member] | Equity Investments [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 2,041,413  
Fair Value, Inputs, Level 3 [Member] | Investments in Affiliated Investee Funds [Member] | Measurement Input WACC [Member] | Valuation Technique, Discounted Cash Flow [Member] | BXINFRA Aggregator (CYM) L.P. [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 776,568