v3.20.4
Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Jan. 01, 2020
Jan. 01, 2019
Dec. 31, 2020
Dec. 31, 2019
Summary of Accounting and Financial Policies [Line Items]        
Firm's revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's total non-interest revenues     45.00% 45.00%
Investment Banking revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's investment banking revenues     90.00% 85.00%
Investment management revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's investment management revenue     95.00% 95.00%
Cash and due from banks     $ 11,950 $ 12,570
Interest-bearing deposits with banks     143,890 120,980
Cash segregated for regulatory and other purposes     24,520 22,780
Receivable from customers and counterparties     82,390 50,900
Receivables from brokers, dealers and clearing organizations     38,940 23,710
Firm's receivables from contracts with clients     2,600 2,270
Payables to customers and counterparties     183,570 170,210
Payables to brokers, dealers and clearing organizations     7,090 4,610
Lease liabilities     $ 2,283 $ 2,385
Operating Lease, Liability, Statement of Financial Position [Extensible List]     us-gaap:OtherLiabilities  
Maximum [Member]        
Summary of Accounting and Financial Policies [Line Items]        
Annual average revenues associated with known remaining performance obligations     $ 250  
Accounting Standards Update 2016-02 [Member]        
Summary of Accounting and Financial Policies [Line Items]        
Lease liabilities   $ 1,770    
New accounting standards impact on retained earnings   $ 12    
Accounting Standards Update 2016-13 [Member]        
Summary of Accounting and Financial Policies [Line Items]        
New accounting standards impact on retained earnings $ (638)      
Accounting Standards Update 2016-13 [Member] | Maximum [Member]        
Summary of Accounting and Financial Policies [Line Items]        
Allowance for credit losses 848      
Accounting Standards Update 2016-13 [Member] | Minimum [Member]        
Summary of Accounting and Financial Policies [Line Items]        
Allowance for credit losses $ (169)