Annual report pursuant to Section 13 and 15(d)

DERIVATIVE INSTRUMENTS AND RISK MANAGEMENT - Additional Information (Detail)

v3.20.4
DERIVATIVE INSTRUMENTS AND RISK MANAGEMENT - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Derivative [Line Items]    
Commodity Asset $ 0  
Derivative Instrument Recognition Period 10 years  
Hedge margin liabilities $ 146,000,000 $ 495,000,000
Collateral required to be posted with counterparties 158,000,000 0
Aggregate fair value additional collateral $ 0  
Maximum term over hedging exposures to the variability of cash flow 12 years  
Pre-tax gains related to cash flow hedges that are currently deferred in AOCI and are expected to be reclassified to income over the 12 month period ended December 31, 2012 $ 11,000,000  
Fair Value, Inputs, Level 1    
Derivative [Line Items]    
Derivative Assets (Liabilities), at Fair Value, Net 0 0
Fair Value, Inputs, Level 3    
Derivative [Line Items]    
Derivative Assets (Liabilities), at Fair Value, Net 0 $ 0
Fair Value | Designated as Hedging Instrument | Other non-current liabilities    
Derivative [Line Items]    
Derivative Liability, Fair Value, Gross Liability $ 7,000,000