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Severance (Tables)
3 Months Ended
Mar. 31, 2021
Restructuring and Related Activities [Abstract]  
Schedule of Changes in Accrued Liabilities for Severance Expenses
Changes in our accrued liabilities for severance expenses were as follows:

Severance
 (Dollars in millions)
Balance at December 31, 2020$103 
Accrued to expense— 
Payments, net(25)
Balance at March 31, 2021$78