Summary of Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Payables And Accruals [Abstract]
Salaries, wages, payroll taxes and benefits	$ 53,329	$ 45,836
Workers' compensation liability	77,773	74,975
Property, sales, use and other taxes	14,754	12,367
Insurance, other than workers' compensation	11,177	10,129
Accrued interest payable	13,713	7,604
Other	12,198	9,546
Accrued expenses	$ 182,944	$ 160,457