XML 138 R93.htm IDEA: XBRL DOCUMENT v3.20.4
Fair Value of Assets and Liabilities - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Commitments to invest in limited partnership interests $ 2,933 $ 2,837
Fixed income securities 66,354 59,044
Fair Value    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Commitments to invest in limited partnership interests $ 395  
Fair Value | Minimum    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Investment assets, useful life 10 years  
Fair Value | Maximum    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Investment assets, useful life 12 years  
Fixed Income Securities Valued Based on Nonbinding Broker Quotes    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Total assets at fair value $ 93 50
Municipal Not Rated by Third Party Credit Rating Agencies    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Total assets at fair value 35 36
Significant unobservable inputs (Level 3)    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Total assets at fair value 832 738
Significant unobservable inputs (Level 3) | Recurring    
Fair value of assets and liabilities measured on recurring and non-recurring basis    
Fixed income securities $ 379 342
Total assets at fair value   $ 738