v3.20.4
Revenue - Schedule of Estimated Investment Advisory, Administration Fees Expected to be Recognized in Future, Related to Unsatisfied Portion of Performance Obligations (Detail) - Investment Advisory, Administration Fees and Securities Lending Revenue [Member] - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation $ 511 $ 367
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01    
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period   1 year
Revenue, Remaining Performance Obligation   $ 98
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01    
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1 year 1 year
Revenue, Remaining Performance Obligation $ 148 $ 88
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01    
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1 year 1 year
Revenue, Remaining Performance Obligation $ 144 $ 74
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01    
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1 year
Revenue, Remaining Performance Obligation $ 112 $ 107
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01    
Schedule of Investment Advisory Administration Fees and Performance Fees by Type [line Items]    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period  
Revenue, Remaining Performance Obligation $ 107