Financial Instruments (Narrative) (Details) (USD $)	Dec. 31, 2011
Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	$ 275,000,000
Fair Value, Inputs, Level 1 [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Amount Outstanding	200,000,000
Fair Value, Inputs, Level 1 [Member] | Notes Payable, Other Payables [Member]
Line of Credit Facility [Line Items]
Notes Payable, Related Parties, Noncurrent	72,900,000
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Line of Credit Facility [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	500,000
6.25% Senior Notes [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes [Member]
Line of Credit Facility [Line Items]
Notes Payable, Fair Value Disclosures	186,900,000
8.25% Senior Notes [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes [Member]
Line of Credit Facility [Line Items]
Notes Payable, Fair Value Disclosures	$ 157,500,000
8.25% Senior Notes [Member] | Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.25%
6.25% Senior Notes [Member] | Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%