v3.26.1
Fair Value Hierarchy - Amount of Level 3 Investments and Significant Unobservable Inputs Used to Value Such Investments (Detail)
$ in Millions
Mar. 31, 2026
USD ($)
yr
Dec. 31, 2025
USD ($)
yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 1,139,251 $ 963,966
Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ 20,836 20,324
Corporate debt securities | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 4,597 $ 4,279
Corporate debt securities | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 7.00% 6.80%
Corporate debt securities | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 21.70% 19.10%
Corporate debt securities | Level 3 | Yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 10.80% 10.90%
Corporate debt securities | Level 3 | Recovery rate | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 41.00% 20.00%
Corporate debt securities | Level 3 | Recovery rate | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 93.80% 65.00%
Corporate debt securities | Level 3 | Recovery rate | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 58.30% 57.40%
Corporate debt securities | Level 3 | Duration (years) | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 1.0 0.7
Corporate debt securities | Level 3 | Duration (years) | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 7.0 6.5
Corporate debt securities | Level 3 | Duration (years) | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 3.6 3.6
Corporate debt securities | Level 3 | Multiples | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 1.3 0.8
Corporate debt securities | Level 3 | Multiples | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 27 43
Corporate debt securities | Level 3 | Multiples | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 6.3 7
Securities backed by real estate | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 309 $ 306
Securities backed by real estate | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 8.70% 8.90%
Securities backed by real estate | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 34.00% 30.80%
Securities backed by real estate | Level 3 | Yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 14.70% 13.30%
Securities backed by real estate | Level 3 | Duration (years) | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 0.2 0.2
Securities backed by real estate | Level 3 | Duration (years) | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 1.8 2.0
Securities backed by real estate | Level 3 | Duration (years) | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 1.7 2.0
Other debt obligations | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 294 $ 345
Other debt obligations | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 5.40% 4.40%
Other debt obligations | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 7.10% 7.60%
Other debt obligations | Level 3 | Yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 6.60% 6.90%
Equity securities | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 9,149 $ 9,481
Equity securities | Level 3 | Multiples | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 0.4 0.4
Equity securities | Level 3 | Multiples | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 25 25
Equity securities | Level 3 | Multiples | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 8.4 8.6
Equity securities | Level 3 | Discount rate/yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 6.00% 6.00%
Equity securities | Level 3 | Discount rate/yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 60.00% 42.00%
Equity securities | Level 3 | Discount rate/yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 13.50% 12.30%
Equity securities | Level 3 | Capitalization rate | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 3.40% 4.40%
Equity securities | Level 3 | Capitalization rate | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 11.50% 11.50%
Equity securities | Level 3 | Capitalization rate | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 5.50% 5.50%