Long Term Obligations (Details Textual) (USD $)	1 Months Ended		12 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Credit Facility Capacity Available		$ 600,000,000
Amount of financing costs recognized as part of income from continuing operations after taxes		2,100,000
Amount of financing costs recognized as part from continuing operations after taxes		1,300,000
Debt instrument interest rate stated percentage rate range minimum			3.90%
Debt instrument interest rate stated percentage rate range maximum			8.00%
Long Term Obligations (Textual) [Abstract]
Senior term notes	100,000,000
Cash amount considered under a swing line borrowing		10,000,000
Aggregate principal amount of revolving commitments	25,000,000
Interest rates on notes payable maturities, minimum			9.00%
Interest rates on notes payable maturities, maximum			10.00%
Federal funds effective interest rate			The base rate for the previous senior term notes existing from May 2005 to August 2010 is the higher of (a) Wells Fargo’s prime rate or (b) the Federal funds rate plus 0.5%. The base rate for the senior term notes, existing from August 2010 to August 2011, and the amended notes existing since August 2011, is a rate per annum equal to the greatest of Wells Fargo’s prime rate in effect on such day, the Federal funds effective rate in effect on such day plus 0.5% and the adjusted Eurodollar rate for a one-month interest period commencing on such day plus 1.0%. The adjusted Eurodollar rate is defined as the rate per annum obtained by dividing (1) the rate of interest offered to Wells Fargo on the London interbank market by (2) a percentage equal to 100% minus the stated maximum rate of all reserve requirements applicable to any member bank of the Federal Reserve System in respect of “Eurocurrency liabilities.”
Interest rate on borrowings under the senior term notes and the revolving credit facility			the base rate (as defined below) plus the applicable margin. The applicable margin for a base rate loan is an amount equal to the applicable margin for Eurodollar rate (as defined below) minus 1.00%; or the adjusted Eurodollar rate (as defined below) plus a margin of 1.50% per annum for the senior term notes existing from May 2005 to August 2010, for the senior term notes existing from August 2010 to August 2011 a margin of 2.25% per annum and for the senior term notes existing since August 2011 until the date of delivery of the compliance certificate and the financial statements for the period ending September 30,2011, a percentage, per annum
Quarterly principal payments on the senior term notes during the first two years beginning 12/31/2011			7,300,000
Quarterly principal payments on the senior term notes during the next two years			10,900,000
Quarterly principal payments on the senior term notes for the three quarters prior to maturity			14,500,000
Borrowings under revolving credit facility			0
Financing costs paid	2,900,000		2,944,000	9,112,000
Revolving credit facility maturity date			42601
Revolving Credit [Member]
Debt Instrument [Line Items]
Revolving credit facility	125,000,000	100,000,000
Amended Credit Facility [Member]
Debt Instrument [Line Items]
Amount of financing costs recognized as part of income from continuing operations after taxes	865,000
Deferred financing costs	2,000,000
Capitalized Deferred financing costs associated with lenders	1,100,000
LIBOR + 1.75% or 2.0% at December 31, 2011
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate			1.75%
Senior term note interest rate, period end			2.00%
LIBOR + 2.25% or 2.5% at December 31, 2010
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate				2.25%
Senior term note interest rate, period end				2.50%
Eurodollar Rate [Member]
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate			0.10%
Prior Senior Term Notes [Member]
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate			1.50%
Secured Seller Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate stated percentage rate range minimum			9.00%
Debt instrument interest rate stated percentage rate range maximum			10.00%
Senior Term Notes [Member]
Debt Instrument [Line Items]
Revolving credit facility	581,300,000
Senior term notes		$ 500,000,000
Fixed charge coverage ratio			1.78 to 1.00
Fixed charge coverage required ratio			No less than 1.20 to 1.00
Leverage Ratio			2.14 to 1.00
Required leverage ratio			No more than 3.00 to 1.00
Current Senior Term Notes [Member]
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate			2.25%