Property and Equipment

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and Equipment

The major classes of property and equipment are as follows:

	Estimated Useful Lives	As of December 31,
		2018			2017
Land(a)	—	$	1,981		$	1,859
Buildings	40 years	134			119
Communications infrastructure assets	1-20 years	18,709			17,184
Information technology assets and other	2-7 years	443			372
Construction in process	—	975			899
Total gross property and equipment		22,242			20,433
Less: accumulated depreciation		(8,566		)	(7,500		)
Total property and equipment, net		$	13,676		$	12,933

(a) Includes land owned in fee and perpetual easements.

Depreciation expense for the years ended December 31, 2018, 2017 and 2016 was $1.1 billion, $915 million and $833 million, respectively. Capital leases and associated leasehold improvements related to gross property and equipment, and accumulated depreciation was $4.4 billion and $1.9 billion, respectively, as of December 31, 2018. See notes 1 and 2, including discussion of the Company's prepaid master lease agreements.