Long Term Debt (Details Textual) (USD $)	0 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended										0 Months Ended		9 Months Ended		9 Months Ended				9 Months Ended			9 Months Ended		0 Months Ended								0 Months Ended
	Feb. 14, 2013	Jan. 24, 2011	Feb. 14, 2013	Mar. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Term Loan, due 2019		Feb. 14, 2013 Term Loan, due 2019	Dec. 31, 2012 Term Loan, due 2019		Sep. 30, 2013 Senior Secured Notes due 2019	Feb. 14, 2013 Senior Secured Notes due 2019	Feb. 14, 2013 Revolving Credit Facility Letter of Credit	Feb. 14, 2013 Revolving Credit Facility Line of Credit covenants	Feb. 14, 2013 Term Loan, due 2019 Notes Payable to Banks	Jan. 24, 2011 Term Loan, due 2019 Term Loan under the Credit Agreement	Sep. 30, 2013 Condition One	Sep. 30, 2012 Condition One	Sep. 30, 2013 Condition One Term Loan under the Credit Agreement	Sep. 30, 2013 Condition Two, Subcondition One	Sep. 30, 2012 Condition Two, Subcondition One	Sep. 30, 2012 Condition Two, Subcondition Two	Sep. 30, 2013 Condition Two, Subcondition Three	Sep. 30, 2012 Condition Two, Subcondition Three	Feb. 14, 2013 Senior Secured Notes Due 2019	Sep. 30, 2013 Line of Credit	Jan. 24, 2011 Line of Credit	Jan. 24, 2011 Line of Credit Years 1-3	Feb. 14, 2013 Maximum Revolving Credit Facility Line of Credit	Feb. 14, 2013 Maximum Term Loan, due 2019 Notes Payable to Banks	Feb. 14, 2013 Minimum Revolving Credit Facility Line of Credit	Feb. 14, 2013 Minimum Term Loan, due 2019 Notes Payable to Banks	Feb. 14, 2013 Federal Funds Effective Rate	Feb. 14, 2013 London Interbank Offered Rate (LIBOR)	Feb. 14, 2013 London Interbank Offered Rate (LIBOR) Senior Secured Notes Due 2019 Term Loan, due 2019	Feb. 14, 2013 Commitment Fee, Period One Revolving Credit Facility Line of Credit	Feb. 14, 2013 Commitment Fee, Period Two Revolving Credit Facility Line of Credit	Feb. 14, 2013 Debt Instrument, Redemption, Period Six Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 15, 2013 Debt Instrument, Redemption, Period Six Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 14, 2013 Mandatory Repayments, Period One Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 14, 2013 Mandatory Repayments, Subsequent Periods Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 15, 2013 Debt Instrument, Redemption Period Four Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 15, 2013 Debt Instrument, Redemption, Period Five Senior Secured Notes Due 2019 Term Loan, due 2019 Notes Payable to Banks	Feb. 15, 2013 Debt Instrument, Redemption, Period One Senior Secured Notes Due 2019	Jan. 24, 2011 Bank of America Syndicate Revolving Credit Facility Senior Secured Credit Facility	Jan. 24, 2011 Bank of America Syndicate Line of Credit Senior Secured Credit Facility
Schedule of Available-for-sale Securities [Line Items]
Debt Issuance Cost, Weighted Average Amortization Period, Effective Interest Method	6 years 2 months 12 days	3 years 8 months 12 days
Long Term Debt (Textual) [Abstract]
Unamortized Discount							$ 17,770,000	[1],[2]	$ 17,800,000	$ 0	[1]
Remaining borrowing capacity					59,100,000
Letter of credit outstanding					15,900,000
Refinancing [Abstract]
Debt Instrument, Face Amount													300,000,000.0				1,000,000,000.0									300,000,000.0
Stated interest rate												8.75%	8.75%													8.75%				5.50%	6.25%	4.50%	5.25%
Line of of credit facility oustanding														40,000,000.0	75,000,000.0
Long-term debt					919,030,000	957,000,000										640,000,000.0
Line of credit facility additional borrowings																640,000,000.0
Repayments of Debt			946,500,000
Interest Paid			7,700,000
Payments of Debt Issuance Costs			32,600,000
Maximum borrowing capacity																															200,000,000.0															75,000,000.0	1,075,000,000.0
Loan origination fees of Revolving Facility for future years																													1,500,000
Minimum floor interest rate on Term Loan under condition one																				2.00%
Interest rate in addition to Libor under subcondition two of condition two																							0.50%
Base interest rate under condition					LIBOR													LIBOR			Bank of America's prime rate			LIBOR
Point in addition to base interest rate under condition																			4.50%			3.50%			1.00%									0.50%	1.00%	1.25%
Debt Instrument, Fronting Fee, Percentage																																0.125%
Percentage commitment fee on average daily unused portion of exit revolving facility																											0.75%										0.50%	0.375%
Debt Instrument, Periodic Payment, Principal				10,500,000		43,000,000																																	1,600,000
Debt Instrument, Mandatory Repayments, Percentage of Excess Cash Flow																																									50.00%	25.00%
Debt Instrument, Redemption Price, Percentage																																								101.00%			103.00%	102.00%	108.75%
Debt Instruments, Retrictive Covenants, Number															2
Debt Instrument, Default Redemption, Percent of Principal																																													100.00%
Debt Instrument, Principal, Redemption Percentage, Maximum																																													35.00%
Debt Issue Costs [Abstract]
Deferred Finance Costs, Noncurrent, Gross	7,600,000		7,600,000
Deferred Finance Costs, Gross																												2,400,000
Deferred Finance Costs, Noncurrent, Net					$ 7,378,000	$ 1,111,000

[1] The $17.8 million discount on the New Term Loan (as defined below) is being amortized using the effective interest method over the term of the senior secured credit facility due 2019.

[2] The carrying amount of the New Term Loan is net of the discount of $17.8 million.