Property, Plant and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

A summary of property, plant and equipment is shown below (in thousands):



	Estimated Life	December 31, 2016			December 31, 2015
	(in years)
Land	—	$	35,217		$	35,632
Buildings	40	215,897			211,115
Central office equipment	7 – 10	662,042			635,208
Outside communications plant	15 – 35	1,191,142			1,161,042
Furniture, vehicles and other work equipment	5 – 15	257,337			258,749
Plant under construction	—	99,568			81,096
Other	—	16,029			17,144
Total property, plant and equipment		2,477,232			2,399,986
Less: Accumulated depreciation		(1,452,880		)	(1,281,205		)
Net property, plant and equipment		$	1,024,352		$	1,118,781

Depreciation expense, excluding amortization of intangible assets, for the years ended December 31, 2016, 2015 and 2014 was $211.3 million, $212.8 million and $209.7 million, respectively. Depreciation expense includes amortization of assets recorded under capital leases.

The Company recorded $0.6 million of asset retirement obligations during the year ended December 31, 2015. Net accretion expense, revisions in cash flow estimates and liability settlements were insignificant during the year. The Company's asset retirement obligations are included as a component of other accrued liabilities or other long-term liabilities in the consolidated balance sheets based on the expected timing of the obligation. As of December 31, 2016, the Company's asset retirement liability of $4.8 million consisted of $0.3 million in other accrued liabilities and $4.5 million in other long-term liabilities. As of December 31, 2015, the Company's asset retirement liability of $4.9 million consisted of $0.8 million in other accrued liabilities and $4.1 million in other long-term liabilities.