Severance and Leased Real Estate (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Schedule of changes in accrued liabilities for severance expenses and leased real estate

Changes in our accrued liabilities for severance expenses and leased real estate were as follows:

	Severance			Real Estate
	(Dollars in millions)
Balance at December 31, 2015	$	14		80
Accrued to expense	173			4
Payments, net	(89		)	(20	)
Reversals and adjustments	—			3
Balance at December 31, 2016	98			67
Accrued to expense	42			4
Liabilities assumed in acquisition of Level 3	1			4
Payments, net	(108		)	(13	)
Reversals and adjustments	—			2
Balance at December 31, 2017	$	33		64