Employee Benefit Plans - Multiemployer Plan and Year with Employer's Total Contribution Greater Than 5% (Detail)	12 Months Ended
	Dec. 31, 2012
Distributors Association Warehousemens Pension Trust [Member]
Multiemployer Plans [Line Items]
Year Contributions to Plan Exceeded 5% of Total Contributions (as of Plan's Year End)	5/31/2011 and 5/31/2010
Local 731 Private Scavengers and Garage Attendants Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Year Contributions to Plan Exceeded 5% of Total Contributions (as of Plan's Year End)	9/30/2011 and 9/30/2010
Suburban Teamsters of Northern Illinois Pension Plan [Member]
Multiemployer Plans [Line Items]
Year Contributions to Plan Exceeded 5% of Total Contributions (as of Plan's Year End)	12/31/2011 and 12/31/2010