Summary of Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Accrued Liabilities [Line Items]
Salaries, wages, payroll taxes and benefits	$ 38,601	$ 58,692
Workers' compensation liability	65,778	66,121
Property, sales, use and other taxes	12,591	11,850
Insurance, other than workers' compensation	7,988	6,012
Accrued interest payable	8,429	4,937
Deferred revenue-current	6,944	7,229
2009 Performance Unit Awards	1,719	3,640
Other	10,392	6,148
Accrued expenses	$ 152,442	$ 164,629