Fair Value Measurements (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Asset Impairment Charges	$ 17,515,000	$ 22,951,000	$ 0
Long-term Debt, Fair Value	2,956,900,000	2,638,200,000
Bank Credit Facility, Fair Value Disclosure, Significant Assumptions	The carrying value of our revolving bank credit facility approximates fair value, as it is subject to short-term floating interest rates that approximate the rates available to us for those periods.
Faustina Investment Impairment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Asset Impairment Charges	$ 15,100,000