v3.20.4
Significant Accounting Policies - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
Segment
shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Oct. 06, 2020
shares
Significant Accounting Policies [Line Items]        
Fair value of loaned securities $ 15,200 $ 14,400    
Fair value of collateral held for loan securities 16,500 15,500    
Reduction of management fees $ 35      
Discrete income tax benefit for vested stock awards   28    
Preferred stock, shares outstanding | shares 0     0
Number of business segments | Segment 1      
Restricted Stock Units (RSUs) [Member]        
Significant Accounting Policies [Line Items]        
Discrete income tax benefit for vested stock awards $ 36 $ 23 $ 64  
Minimum [Member]        
Significant Accounting Policies [Line Items]        
VIE, economic interest percentage 10.00%      
Collateral cash and securities received in exchange of value of securities lent in order to reduce counterparty risk 102.00%      
Maximum [Member]        
Significant Accounting Policies [Line Items]        
Collateral cash and securities received in exchange of value of securities lent in order to reduce counterparty risk 112.00%      
Maximum [Member] | Software [Member]        
Significant Accounting Policies [Line Items]        
Estimated useful life 3 years      
ASU 2016-13 [Member]        
Significant Accounting Policies [Line Items]        
Change in accounting principle, accounting standards update, adopted true      
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020      
Change in accounting principle, accounting standards update, immaterial effect true