Operating Property (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 25, 2010	Dec. 26, 2009
Operating Property [Abstract]
Land	$ 7,982,000	$ 7,982,000
Leasehold improvements	10,180,000	10,038,000
Buildings and improvements	23,875,000	23,520,000
Trailing equipment	204,117,000	188,176,000
Other equipment	41,796,000	40,763,000
Property, Plant and Equipment, Gross, Total	287,950,000	270,479,000
Less accumulated depreciation and amortization	145,804,000	137,830,000
Property, Plant and Equipment, Net, Total	142,146,000	132,649,000
Operating property under capital leases	112,599,000	114,017,000
Operating property under capital leases, net of accumulated amortization	76,603,000	70,154,000
Capital leases	$ 34,044,000	$ 14,986,000	$ 12,284,000