Commitments And Contingencies (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012	Oct. 31, 2012
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
Final settlement		7,400,000
Additional expense		1,500,000
Rent expense	16,900,000	18,200,000	18,500,000
Salary and incentive program severance multiplier	3
Self insurance deductible for workers compensation	5,000,000
Self insurance deductible for general liability claims	1,000,000
Self insurance deductible for medical and dental coverage	400,000
Workers' compensation self-insured risk reserve, short-term	9,100,000	7,000,000
Workers' compensation self-insured risk reserve, long-term	16,800,000	11,300,000
Self insured risk accruals	33,400,000	26,100,000
Receivable for Medical and Dental Coverage	14,000	230,000
Minimum
Loss Contingencies [Line Items]
Severance payment	0.75
Severance payment for the chance of control	1.5
Maximum
Loss Contingencies [Line Items]
Severance payment	1.0
Severance payment for the chance of control	2.0
Chief Executive Officer
Loss Contingencies [Line Items]
Annual salary to Mr. Patterson	$ 650,000
Non-Cancelable Property And Equipment | Minimum
Loss Contingencies [Line Items]
Term of operating leases	12 months
Non-Cancelable Property And Equipment | Maximum
Loss Contingencies [Line Items]
Term of operating leases	60 months
Well service units and equipment | Maximum
Loss Contingencies [Line Items]
Term of operating leases	99 years