Summary of Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Accrued Liabilities [Line Items]
Salaries, wages, payroll taxes and benefits	$ 50,667	$ 55,430
Workers' compensation liability	68,346	68,441
Property, sales, use and other taxes	8,692	9,749
Insurance, other than workers' compensation	5,427	10,419
Accrued interest payable	7,590	7,664
Deferred revenue-current		1,523
Other	5,379	5,406
Accrued expenses	$ 146,101	$ 158,632