v3.20.4
Property and Equipment - Asset Retirement Obligation (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Asset retirement obligations, beginning of year $ 659 $ 609  
Fair value of liabilities acquired through Merger 1,110 0  
Liabilities incurred 16 35  
Liabilities settled (40) (2)  
Accretion expense 55 32  
Changes in estimated cash flows 17 (15)  
Asset retirement obligations, end of period 1,817 659 $ 609
Asset retirement costs capitalized, net 912 159  
Non-cash impairment related to capitalized software development costs 200 0 $ 0
Other long-term liabilities      
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Asset retirement obligations, beginning of year 659    
Asset retirement obligations, end of period 1,803 659  
Other current liabilities      
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Asset retirement obligations, beginning of year 0    
Asset retirement obligations, end of period $ 14 $ 0