v3.20.4
Derivatives and Hedging Activities - Fair Value of Derivatives, Level 3 Rollforward (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance $ 25 $ 590
Net Realized Gains / (Losses) 226 118
Net Unrealized Gains / (Losses) 612 (454)
Purchases 319 444
Sales (724) (668)
Settlements 750 236
Transfers Into Level 3 (40) 7
Transfers Out Of Level 3 7 (248)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance 1,175 25
Interest Rate Contract [Member]    
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance 89 (109)
Net Realized Gains / (Losses) 12 (24)
Net Unrealized Gains / (Losses) 226 199
Purchases 12 8
Sales (28) (13)
Settlements (34) 40
Transfers Into Level 3 (13)  
Transfers Out Of Level 3 3 (12)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance 267 89
Credit Risk Contract [Member]    
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance 1,877 1,672
Net Realized Gains / (Losses) 28 42
Net Unrealized Gains / (Losses) 110 273
Purchases 39 146
Sales (50) (114)
Settlements (229) (251)
Transfers Into Level 3 47 108
Transfers Out Of Level 3 (44) 1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance 1,778 1,877
Foreign Exchange Contract [Member]    
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance (211) 461
Net Realized Gains / (Losses) (8) (32)
Net Unrealized Gains / (Losses) (210) (327)
Purchases 1 11
Sales (20) (1)
Settlements 117 (306)
Transfers Into Level 3 (2) (14)
Transfers Out Of Level 3 (5) (3)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance (338) (211)
Commodity Contract [Member]    
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance 247 112
Net Realized Gains / (Losses) (12) (34)
Net Unrealized Gains / (Losses) 159 219
Purchases 37 25
Sales (22) (81)
Settlements (60) (6)
Transfers Into Level 3 (27) 8
Transfers Out Of Level 3 (22) 4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance 300 247
Equity Contract [Member]    
Derivative [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance (1,977) (1,546)
Net Realized Gains / (Losses) 206 166
Net Unrealized Gains / (Losses) 327 (818)
Purchases 230 254
Sales (604) (459)
Settlements 956 759
Transfers Into Level 3 (45) (95)
Transfers Out Of Level 3 75 (238)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance $ (832) $ (1,977)