Property and equipment - Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 80,669	$ 88,276
Less accumulated depreciation	28,148	34,911
Property, Plant and Equipment, Net, Total	52,521	53,365
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	14,549	15,449
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	35,606	37,570
Leasehold interests and improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	240	284
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	26,693	27,135
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 3,581	$ 7,838