v3.21.2
Derivatives and Hedging Activities - Fair Value, Derivatives, Measurement Inputs, Disclosure (Detail)
$ in Millions
Sep. 30, 2021
USD ($)
MMBTU
$ / bbl
Jun. 30, 2021
USD ($)
Dec. 31, 2020
USD ($)
$ / bbl
MMBTU
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Dec. 31, 2019
USD ($)
Fair Value Measurement Inputs Disclosure [Line Items]            
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance | $ | $ $ 649 $ 567 $ 1,175 $ 2,154 $ 3,060 $ 25
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 | $ | $ $ 247 308 $ 267 255 311 89
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Average Correlation [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.63   0.56      
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Median Correlation [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.62   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   0.65      
Interest Rate Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.54   0.53      
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 | $ | $ $ 1,719 1,750 $ 1,778 1,986 2,327 1,877
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 1.13   1.09      
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 0.87   0.74      
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   0.40      
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   0.30      
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 0.47   0.46      
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   0.40      
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 | $ | $ $ (119) (234) $ (338) (255) (94) (211)
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   0.39      
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   0.41      
Foreign Exchange Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.20   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 0.20   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 | $ | $ $ 513 266 $ 300 195 331 247
Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.37   0.32      
Commodity Contract [Member] | Level 3 [Member] | Measurement Input, Median Volatility [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.33   0.30      
Commodity Contract [Member] | Electricity [Member] | Level 3 [Member] | Measurement Input, Average Spread [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 34.19          
Commodity Contract [Member] | Electricity [Member] | Level 3 [Member] | Measurement Input, Median Spread [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 35.69          
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 (0.07)   (0.13)      
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 (0.03)   (0.09)      
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 (0.84)   9.73      
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 (0.84)   9.55      
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 | $ | $ $ (1,711) $ (1,523) $ (832) $ (27) $ 185 $ (1,977)
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Average Correlation [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.62   0.52      
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Median Correlation [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.71   0.55      
Equity Contract [Member] | Level 3 [Member] | Measurement Input, Average Volatility [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.18   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 0.19   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 0.25   (0.08)      
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 0.01   0.02      
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 0.02   0.07      
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 0.20   0.25      
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 0.20   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   0.15      
Minimum [Member] | Commodity Contract [Member] | Electricity [Member] | Level 3 [Member] | Measurement Input, Spread [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 9.95          
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 (1.39)   (1.00)      
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 (0.93)   8.30      
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 0.04   0.03      
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 5.76   6.99      
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 1   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   0.90      
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 0.20   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 1.52   0.87      
Maximum [Member] | Commodity Contract [Member] | Electricity [Member] | Level 3 [Member] | Measurement Input, Spread [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 55.76          
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 4.36   2.13      
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 (0.74)   11.20      
Maximum [Member] | Equity Contract [Member] | Level 3 [Member] | Measurement Input, Correlation [Member]            
Fair Value Measurement Inputs Disclosure [Line Items]            
Assets (Liabilities) significant unobservable Inputs 0.99   1      
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 1.53   1.29