Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss Contingencies [Line Items]
Environmental violations, fines and penalties	$ 1,400,000
Potential liability audit ranges Minimum	5,900,000
Potential liability audit ranges Maximum	7,300,000
Accrual estimated liability	5,900,000
Rent expense	18,500,000	17,200,000	12,800,000
Salary and incentive program severance multiplier	3
Self insurance deductible for workers compensation	1,000,000
Self insurance deductible for general liability claims	1,000,000
Self insurance deductible for medical and dental coverage	300,000
Workers' compensation self-insured risk reserve, short-term	5,900,000	5,000,000
Workers' compensation self-insured risk reserve, long-term	6,900,000	5,500,000
Self insured risk accruals	22,900,000	19,700,000
Receivable for Medical and Dental Coverage	205,000	1,000
Minimum
Loss Contingencies [Line Items]
Severance payment	0.75
Severance payment for the chance of control	1.0
Maximum
Loss Contingencies [Line Items]
Severance payment	1.5
Severance payment for the chance of control	2.0
Chief Executive Officer
Loss Contingencies [Line Items]
Annual salary to Mr. Huseman	$ 700,000
Non-Cancelable Property And Equipment | Minimum
Loss Contingencies [Line Items]
Term of operating leases	12
Non-Cancelable Property And Equipment | Maximum
Loss Contingencies [Line Items]
Term of operating leases	60
Well Service Units And Equipment | Maximum
Loss Contingencies [Line Items]
Term of operating leases	99