Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Property and Equipment
Property and equipment, gross	$ 1,657,038	$ 1,539,275
Less accumulated depreciation and amortization	755,320	682,863
Property and equipment, net	901,718	856,412
Land [Member]
Property and Equipment
Property and equipment, gross	13,150	11,314
Buildings and improvements [Member]
Property and Equipment
Property and equipment, gross	51,500	47,710
Well service units and equipment [Member]
Property and Equipment
Property and equipment, gross	477,668	447,743
Fluid services equipment [Member]
Property and Equipment
Property and equipment, gross	195,880	179,495
Brine and fresh water stations [Member]
Property and Equipment
Property and equipment, gross	14,068	13,000
Frac/test tanks [Member]
Property and Equipment
Property and equipment, gross	263,018	246,816
Pressure pumping equipment [Member]
Property and Equipment
Property and equipment, gross	266,582	246,931
Construction equipment [Member]
Property and Equipment
Property and equipment, gross	29,388	29,281
Contract drilling equipment [Member]
Property and Equipment
Property and equipment, gross	98,166	93,728
Disposal facilities [Member]
Property and Equipment
Property and equipment, gross	85,005	78,632
Vehicles [Member]
Property and Equipment
Property and equipment, gross	58,544	54,238
Rental equipment [Member]
Property and Equipment
Property and equipment, gross	59,071	46,851
Aircraft [Member]
Property and Equipment
Property and equipment, gross	5,034	4,251
Software [Member]
Property and Equipment
Property and equipment, gross	23,945	23,595
Other [Member]
Property and Equipment
Property and equipment, gross	$ 16,019	$ 15,690