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Condensed Financial Statements - Dividends and Distributions (Details) - Parent Company [Member] - USD ($)
$ in Millions
2 Months Ended 12 Months Ended
Feb. 26, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Distribution [Line Items]        
Proceeds from dividends received   $ 2,000 $ 2,000 $ 2,300
Subsequent Event [Member]        
Distribution [Line Items]        
Proceeds from dividends received $ 131