XML 25 R6.htm IDEA: XBRL DOCUMENT v3.20.4
CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Statement of Financial Position [Abstract]    
Allowance for doubtful accounts $ 45 $ 13
Accumulated depreciation $ 2,818 $ 1,825