v3.20.4
Overview - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 11, 2020
USD ($)
shares
Dec. 08, 2020
USD ($)
Sep. 09, 2020
USD ($)
shares
Sep. 01, 2020
USD ($)
Aug. 10, 2020
Feb. 19, 2020
USD ($)
shares
Dec. 31, 2020
USD ($)
Segment
shares
Dec. 31, 2019
USD ($)
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]                
Number of operating segment | Segment             2  
Number of reportable segment | Segment             2  
Number of shares issued in public offering | shares           15,200,000    
Stock split ratio         5   5  
Stock split, dividend description             five-for-one stock split effected in the form of a stock dividend in August 2020  
Proceeds from issuances of common stock in public offerings, net of issuance costs           $ 2,310 $ 12,269 $ 848
Common stock public offering issuance costs           $ 28    
Common stock issuance value             $ 12,269  
Common Stock [Member]                
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]                
Number of shares issued in public offering | shares [1]             34,000,000  
Common stock issuance value [1]             $ 0  
At-the-Market Offering Program [Member] | Common Stock [Member]                
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]                
Proceeds from issuances of common stock in public offerings, net of issuance costs $ 5,000   $ 5,000          
Common stock issuance value   $ 5,000   $ 5,000        
Sale of common stock, number of shares | shares 7,915,589   11,141,562          
Net proceeds from Issuance of common stock $ 4,990   $ 4,970          
Sales agents? commissions 13   25          
Other offering costs $ 1   $ 1          
[1]

Prior period results have been adjusted to reflect the five-for-one stock split effected in the form of a stock dividend in August 2020. See Note 1, Overview, for details regarding stock split and public offerings.