XML 48 R24.htm IDEA: XBRL DOCUMENT v3.20.4
Schedule II - Valuation and Qualifying Accounts
 12 Months Ended
Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]  
Schedule II - Valuation and Qualifying Accounts
Schedule II
Valuation and Qualifying Accounts
For the Years Ended December 31, 2020, 2019 and 2018 
(In millions)
 
Description
Balance at
Beginning of
Period		Additions
Charged to
Costs and
Expenses		DeductionsOtherBalance at
End of
Period
Allowance for credit losses - receivables:
2020$9 $70 $16 $15 $78 
20198 17 16 — 9 
20187 17 16 — 8 
Obsolescence allowance—spare parts:
2020$425 $88 $35 $— $478 
2019412 76 63 — 425 
2018354 73 15 — 412 
Allowance for credit losses - notes receivable:
2020$— $518 $— $4 $522 
Valuation allowance for deferred tax assets:
2020$58 $197 $8 $— $247 
201959 — 1 — 58 
201863 2 6 — 59