v3.25.4
Fair Value Hierarchy - Amount of Level 3 Investments and Significant Unobservable Inputs Used to Value Such Investments (Detail)
$ in Millions
Dec. 31, 2025
USD ($)
yr
Dec. 31, 2024
USD ($)
yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 963,966 $ 907,669
Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ 20,324 20,358
Corporate debt securities | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 4,279 $ 4,510
Corporate debt securities | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 6.80% 5.00%
Corporate debt securities | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 19.10% 28.80%
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% 12.20%
Corporate debt securities | Level 3 | Recovery rate | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 20.00% 5.80%
Corporate debt securities | Level 3 | Recovery rate | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 65.00% 41.00%
Corporate debt securities | Level 3 | Recovery rate | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 57.40% 25.20%
Corporate debt securities | Level 3 | Duration (years) | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 0.7 0.3
Corporate debt securities | Level 3 | Duration (years) | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 6.5 9.0
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 0.8 1.1
Corporate debt securities | Level 3 | Multiples | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 43 34.2
Corporate debt securities | Level 3 | Multiples | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 7 6.5
Securities backed by real estate | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 306 $ 562
Securities backed by real estate | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 8.90% 9.50%
Securities backed by real estate | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 30.80% 16.00%
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 13.30% 13.60%
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 1.1
Securities backed by real estate | Level 3 | Duration (years) | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input | yr 2.0 2.8
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 2.0 2.8
Other debt obligations | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 345 $ 328
Other debt obligations | Level 3 | Yield | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 4.40% 7.00%
Other debt obligations | Level 3 | Yield | Investments | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 7.60% 8.70%
Other debt obligations | Level 3 | Yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 6.90% 7.70%
Equity securities | Level 3 | Investments    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total financial assets at fair value | $ $ 9,481 $ 8,742
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 34.2
Equity securities | Level 3 | Multiples | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investments, measurement input 8.6 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 42.00% 27.90%
Equity securities | Level 3 | Discount rate/yield | Investments | Weighted Average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 12.30% 13.30%
Equity securities | Level 3 | Capitalization rate | Investments | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Percentage of investments, measurement input 4.40% 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% 9.10%
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% 5.40%