Significant Accounting Policies (Detail Textuals 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Defined Benefit Pension Plan	Dec. 31, 2012 Operating equipment Minimum	Dec. 31, 2012 Operating equipment Maximum	Dec. 31, 2012 Buildings and leasehold improvements Minimum	Dec. 31, 2012 Buildings and leasehold improvements Maximum	Dec. 31, 2012 Furniture and fixtures Minimum	Dec. 31, 2012 Furniture and fixtures Maximum	Dec. 31, 2012 Software	Dec. 31, 2012 Vehicles Minimum	Dec. 31, 2012 Vehicles Maximum	Dec. 31, 2008 Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of interest rate swap agreement														$ 50,000,000
Estimated useful lives of the assets					3 years	10 years	15 years	30 years	5 years	7 years	5 years	3 years	5 years
Depreciation method used for property, plant and equipment	straight-line basis
Goodwill	24,093,000	24,093,000
Advertising expenses	$ 2,965,000	$ 2,406,000	$ 1,782,000
Defined benefit pension plan eligibility criteria				Defined benefit pension plan that provides monthly benefits upon retirement at age 65 to eligible employees with at least one year of service prior to 2002