Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2018

Property Plant And Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment at March 31, 2018 and December 31, 2017 consisted of the following:

	Residual Value as Percentage of Original Cost		Estimated Useful Life in Years	March 31, 2018			December31, 2017
				(In thousands)
Land				$	2,988		$	2,970
Vehicles and machinery	0 - 55%		5 - 30		156,567			151,937
Buildings and improvements (1)	0 - 25		3 - 30		25,918			25,079
Furniture, office and computer equipment		—	3 - 10		74,477			73,416
Property, plant and equipment					259,950			253,402
Accumulated depreciation					(101,672	)		(96,098	)
Property, plant and equipment, net				$	158,278		$	157,304

(1) Improvements made to leased properties are depreciated over the lesser of the estimated remaining life or the remaining term of the respective lease.