Long-Term Debt (Schedule of Long-term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term Debt	$ 534,444	$ 519,597
Long-term Debt, Current Maturities	(23)	(872)
Long-term Debt, Excluding Current Maturities	534,421	518,725
Senior Notes [Member] | Senior Notes, Issued [Member]
Debt Instrument [Line Items]
Long-term Debt	419,332	418,617
Notes Payable, Other Payables [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Long-term Debt	112	980
Revolving Credit Facility [Member] | Senior secured revolving credit facility [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 115,000	$ 100,000