Long-Term Obligations (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 39,002
Long-term Debt, Maturities, Repayments of Principal in Year Two	50,593
Long-term Debt, Maturities, Repayments of Principal in Year Three	54,696
Long-term Debt, Maturities, Repayments of Principal in Year Four	461,407
Long-term Debt, Maturities, Repayments of Principal in Year Five	3,413
Long-term Debt, Maturities, Repayments of Principal after Year Five	21,532
Long-term Debt	592,688	574,330
Capital Lease Obligations	37,955	44,523
Debt Instrument, Basis Spread on Variable Rate	1.75%
Leverage Ratio	2.03
Debt and Capital Lease Obligations	630,643	618,853
Senior Notes [Member]
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	35,774
Long-term Debt, Maturities, Repayments of Principal in Year Two	47,344
Long-term Debt, Maturities, Repayments of Principal in Year Three	51,289
Long-term Debt, Maturities, Repayments of Principal in Year Four	458,281
Long-term Debt, Maturities, Repayments of Principal in Year Five	0
Long-term Debt, Maturities, Repayments of Principal after Year Five	0
Capital Lease Obligations [Member]
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	3,228
Long-term Debt, Maturities, Repayments of Principal in Year Two	3,249
Long-term Debt, Maturities, Repayments of Principal in Year Three	3,407
Long-term Debt, Maturities, Repayments of Principal in Year Four	3,126
Long-term Debt, Maturities, Repayments of Principal in Year Five	3,413
Long-term Debt, Maturities, Repayments of Principal after Year Five	$ 21,532
Leverage Ratio Level One [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	2.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Leverage Ratio	≥ 2.50:1.00
Leverage Ratio Level Two [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.375%
Leverage Ratio	< 2.50:1.00 and ≥ 1.75:1.00
Leverage Ratio Level Three [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Leverage Ratio	< 1.75:1.00 and ≥ 1.00:1.00
Leverage Ratio Level Four [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.20%
Leverage Ratio	< 1.00:1.00