Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,147,046	$ 1,110,862
Less: Accumulated depreciation	(550,436)	(530,720)
Total property, plant and equipment, net	596,610	580,142
Land and land Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	20,900	21,804
Land and land Improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	8 years
Land and land Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	15 years
Buildings and improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	39 years
Property, plant and equipment, gross	67,175	69,827
Rental machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	7 years
Property, plant and equipment, gross	795,211	763,722
Machinery and equipment - other
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	7 years
Property, plant and equipment, gross	62,257	64,648
Furniture, fixtures and computers
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	5 years
Property, plant and equipment, gross	17,983	17,915
Automobiles and other vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	5 years
Property, plant and equipment, gross	38,637	37,417
Aircraft
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	7 years
Property, plant and equipment, gross	14,868	14,868
Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives in Years	7 years
Property, plant and equipment, gross	6,991	6,353
Construction in progress - machinery and equipment and buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 123,024	$ 114,308