Commitments And Contingencies (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Loss Contingencies [Line Items]
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	$ 13,900,000	$ 16,900,000	$ 18,200,000
Salary and incentive program severance multiplier | item	3
Self insurance deductible for workers compensation	$ 2,500,000
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	7,500,000	9,100,000
Workers' compensation self-insured risk reserve, long-term	15,900,000	16,800,000
Self insured risk accruals	30,800,000	33,400,000
Receivable for Medical and Dental Coverage	$ 73,000	$ 14,000
Minimum
Loss Contingencies [Line Items]
Severance payment | item	0.75
Severance payment for the chance of control | item	1.5
Maximum
Loss Contingencies [Line Items]
Severance payment | item	1.0
Severance payment for the chance of control | item	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