Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified				9 Months Ended
	Sep. 30, 2012	Jan. 01, 2012	Dec. 28, 2003	Sep. 30, 2012 Valleycrest Landfill Site	Sep. 30, 2012 Pasco Sanitary Landfill Superfund Site
Commitments and Contingencies Disclosure [Line Items]
Environmental liabilities	$ 4,164	$ 3,753		$ 2,798	$ 1,213
Period of time over which remediation costs are expected to be incurred				30 years	60 years
Amount paid to indemnify against certain future liability			$ 270