Property, Plant and Equipment (Detail) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Land		$ 2,954	$ 2,970
Vehicles and machinery		152,782	151,937
Buildings and improvements	[1]	26,779	25,079
Furniture, office and computer equipment		75,966	73,416
Property, plant and equipment		258,481	253,402
Accumulated depreciation		(102,860)	(96,098)
Property, plant and equipment, net		$ 155,621	$ 157,304
Vehicles and machinery | Minimum
Property Plant And Equipment [Line Items]
Residual Value as Percentage of Original Cost		0.00%
Estimated Useful Life in Years		5 years
Vehicles and machinery | Maximum
Property Plant And Equipment [Line Items]
Residual Value as Percentage of Original Cost		55.00%
Estimated Useful Life in Years		30 years
Buildings and improvements | Minimum
Property Plant And Equipment [Line Items]
Residual Value as Percentage of Original Cost	[1]	0.00%
Estimated Useful Life in Years	[1]	3 years
Buildings and improvements | Maximum
Property Plant And Equipment [Line Items]
Residual Value as Percentage of Original Cost	[1]	25.00%
Estimated Useful Life in Years	[1]	30 years
Furniture, office and computer equipment | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life in Years		3 years
Furniture, office and computer equipment | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life in Years		10 years

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