v3.20.4
Derivatives and Hedging Activities - Fair Value, Derivatives, Measurement Inputs, Disclosure (Detail)
$ in Millions
Dec. 31, 2020
USD ($)
MMBTU
$ / bbl
Dec. 31, 2019
USD ($)
MMBTU
$ / bbl
Dec. 31, 2018
USD ($)
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ 1,175 $ 25 $ 590
Interest Rate Contract [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ 267 $ 89 (109)
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.56 0.52  
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Median Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.60 0.60  
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.65 0.70  
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.53 0.61  
Credit Risk Contract [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ 1,778 $ 1,877 1,672
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Average Credit Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 1.09 0.96  
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Median Credit Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.74 0.53  
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, , Average Upfront Credit Points [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.40 0.38  
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, , Median Upfront Credit Points [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.30 0.32  
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Average Recovery Rate [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.46 0.31  
Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Median Recovery Rate [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.40 0.25  
Foreign Exchange Contract [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ (338) $ (211) 461
Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Average Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.39 0.37  
Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Median Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.41 0.36  
Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.18    
Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.18    
Commodity Contract [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ 300 $ 247 112
Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.32 0.26  
Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.30 0.25  
Commodity Contract [Member] | Natural Gas [Member] | Level 3 [Member] | Measurement Input, Average Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | MMBTU (0.13) (0.16)  
Commodity Contract [Member] | Natural Gas [Member] | Level 3 [Member] | Measurement Input, Median Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | MMBTU (0.09) (0.17)  
Commodity Contract [Member] | Oil [Member] | Level 3 [Member] | Measurement Input, Average Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | $ / bbl 9.73 9.82  
Commodity Contract [Member] | Oil [Member] | Level 3 [Member] | Measurement Input, Median Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | $ / bbl 9.55 11.15  
Equity Contract [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ $ (832) $ (1,977) $ (1,546)
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Average Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.52 0.42  
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Median Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.55 0.45  
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.14 0.14  
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.07 0.07  
Minimum [Member] | Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs (0.08) (0.42)  
Minimum [Member] | Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.31 0.31  
Minimum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Credit Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.02 0.01  
Minimum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Upfront Credit Points [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.07 0.02  
Minimum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Recovery Rate [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.25 0.10  
Minimum [Member] | Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.20 0.20  
Minimum [Member] | Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.18    
Minimum [Member] | Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.15 0.09  
Minimum [Member] | Commodity Contract [Member] | Natural Gas [Member] | Level 3 [Member] | Measurement Input, Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | MMBTU (1.00) (1.93)  
Minimum [Member] | Commodity Contract [Member] | Oil [Member] | Level 3 [Member] | Measurement Input, Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | $ / bbl 8.30 (4.86)  
Minimum [Member] | Equity Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs (0.70) (0.70)  
Minimum [Member] | Equity Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.03 0.02  
Maximum [Member] | Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.81 0.81  
Maximum [Member] | Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 1.50 1.50  
Maximum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Credit Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 6.99 5.59  
Maximum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Upfront Credit Points [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.90 0.90  
Maximum [Member] | Credit Risk Contract [Member] | Level 3 [Member] | Measurement Input, Recovery Rate [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.90 0.60  
Maximum [Member] | Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.70 0.70  
Maximum [Member] | Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.18    
Maximum [Member] | Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 0.87 0.57  
Maximum [Member] | Commodity Contract [Member] | Natural Gas [Member] | Level 3 [Member] | Measurement Input, Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | MMBTU 2.13 1.69  
Maximum [Member] | Commodity Contract [Member] | Oil [Member] | Level 3 [Member] | Measurement Input, Spread [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs | $ / bbl 11.20 19.77  
Maximum [Member] | Equity Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 1 0.99  
Maximum [Member] | Equity Contract [Member] | Level 3 [Member] | Measurement Input, Price Volatility [Member]      
Fair Value Measurement Inputs Disclosure [Line Items]      
Assets (Liabilities) significant unobservable Inputs 1.29 0.72