Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Principles - New Accounting Standards (Details)

v3.20.2
Summary of Significant Accounting Principles - New Accounting Standards (Details)
 3 Months Ended 6 Months Ended
Jan. 01, 2020
USD ($)
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Loan
Jun. 30, 2019
USD ($)
Jun. 30, 2020
USD ($)
Loan
portfolio_segment
Jun. 30, 2019
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Mar. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Impact of adoption     $ 265,637,000,000 $ 271,408,000,000 $ 265,637,000,000 $ 271,408,000,000 $ 264,918,000,000 $ 264,810,000,000 $ 267,010,000,000 $ 265,325,000,000
Allowance for credit losses     21,091,000,000 10,333,000,000 21,091,000,000 10,333,000,000        
Retained earnings     $ (157,578,000,000)   $ (157,578,000,000)     (156,319,000,000)    
Number of portfolio segments | portfolio_segment         3          
Expected credit losses         $ 0          
Number of loans funded under Paycheck Protection Program, CARES Act | Loan     334,000   334,000          
Financing receivable, before credit loss allowance     $ 998,944,000,000   $ 998,944,000,000     983,426,000,000    
Income tax expense (benefit)     266,000,000 $ 1,611,000,000 787,000,000 $ 3,067,000,000        
Cumulative Effect, Period of Adoption, Adjustment                    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Allowance for credit losses $ 3,300,000,000                  
Loans and leases receivable, percentage increase in allowance 32.00%                  
Smalll Business Administration (SBA), CARES Act, Paycheck Protection Program                    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Financing receivable, before credit loss allowance     $ 25,100,000,000   $ 25,100,000,000          
ASU 2020-04                    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Impact of adoption $ 0                  
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment                    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Impact of adoption               $ (2,406,000,000)    
Allowance for credit losses 3,300,000,000                  
Retained earnings $ 2,400,000,000                  
Scenario, Forecast                    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                    
Income tax expense (benefit)   $ (700,000,000)