Property, Plant and Equipment (Table)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, plant and equipment

Property, plant and equipment in service and under construction, and related accumulated depreciation and amortization, as of December 31, 2018 and 2017, were as follows:

December 31,	Useful Lives (Years)	2018			2017
(Dollars in millions)
Land	N/A	$	35		$	36
Buildings	20	296			297
Leasehold and land improvements	1-30	1,210			1,178
Cell site equipment	7-25	3,460			3,411
Switching equipment	5-8	1,018			988
Office furniture and equipment	3-5	285			389
Other operating assets and equipment	3-5	51			57
System development	1-7	1,149			1,060
Work in process	N/A	274			212
Total property, plant and equipment, gross		7,778			7,628
Accumulated depreciation and amortization		(5,576		)	(5,308		)
Total property, plant and equipment, net		$	2,202		$	2,320