Subsequent Events - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Business Combination
Subsequent Event [Line Items]
Subsequent event date	Jul. 13, 2011
Subsequent event description	On July 13, 2011, we entered into an agreement and plan of merger with Edge Oilfield Services, L.L.C. and Summit Oilfield Services, L.L.C. collectively (“Edge”). Edge primarily rents frac stack equipment used to support hydraulic fracturing operations and the associated flow back of frac fluids, proppants, oil and natural gas. It also provides well testing services, rental equipment such as pumps and power swivels, and oilfield fishing services.
Total consideration for acquisition	$ 300.0
Consideration for acquisition, shares of common stock issued	7.5
Consideration for acquisition, cash paid	164.0
Agreed amount to reimburse or fund Edge's pre-closing capital expenditures	40
2011 Credit Facility | Amendment of Credit Facility
Subsequent Event [Line Items]
Senior Secured Credit Facility, aggregate principal amount	550
Senior Secured Credit Facility, optional maximum aggregate principal amount	650
Senior Secured Credit Facility, consolidated total funded indebtedness to total capitalization ratio	50.00%
Senior Secured Credit Facility, anticipated financing costs	1.5
Amendment of Credit Facility
Subsequent Event [Line Items]
Subsequent event date	Jul. 27, 2011
2011 Credit Facility
Subsequent Event [Line Items]
Senior Secured Credit Facility, aggregate principal amount	400
Senior Secured Credit Facility, latest maturity date	March 31, 2016
Senior Secured Credit Facility, optional maximum aggregate principal amount	$ 500
Senior Secured Credit Facility, consolidated total funded indebtedness to total capitalization ratio	45.00%