v3.26.1
Fair Value Hierarchy - Amount of Level 3 Investments and Significant Unobservable Inputs Used to Value Such Investments (Detail)
$ in Millions
Jun. 30, 2026
USD ($)
yr
Mar. 31, 2026
USD ($)
Dec. 31, 2025
USD ($)
yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 1,157,158 $ 1,139,251 $ 963,966
Level 3      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ 20,839 $ 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 | $ $ 4,385   $ 4,279
Corporate debt securities | Level 3 | Yield | Investments | Minimum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Percentage of investments, measurement input 6.20%   6.80%
Corporate debt securities | Level 3 | Yield | Investments | Maximum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Percentage of investments, measurement input 16.20%   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 10.90%   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 3.40%   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 95.40%   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 52.60%   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 7.2   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 3.8   3.6
Corporate debt securities | Level 3 | Multiples | Investments | Minimum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, measurement input 1   0.8
Corporate debt securities | Level 3 | Multiples | Investments | Maximum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, measurement input 25.3   43
Corporate debt securities | Level 3 | Multiples | Investments | Weighted Average      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, measurement input 6.6   7
Securities backed by real estate | Level 3 | Investments      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 310   $ 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 30.90%   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 13.50%   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 1.3   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 1.2   2.0
Other debt obligations | Level 3 | Investments      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 289   $ 345
Other debt obligations | Level 3 | Yield | Investments | Minimum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Percentage of investments, measurement input 5.20%   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 6.40%   6.90%
Equity securities | Level 3 | Investments      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 9,608   $ 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 25.7   25
Equity securities | Level 3 | Multiples | Investments | Weighted Average      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, measurement input 9   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 4.50%   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 50.00%   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 12.70%   12.30%
Equity securities | Level 3 | Capitalization rate | Investments | Minimum      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Percentage of investments, measurement input 4.00%   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 5.60%   5.50%