Fair Value Measurements (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Sensitivity Analysis of Fair Value, Impact of 1 Percent Increase or Decrease in Level 3 Inputs	$ 1,400,000
Other Asset Impairment Charges	0	0	17,515,000
Debt, Fair Value	2,938,600,000	2,957,900,000
Investment Impairment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Asset Impairment Charges	$ 15,100,000