Capital and Financing Transactions - Schedule of the Effect of Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Amount of gain (loss) recognized in other comprehensive income on derivative	$ (10,968)	$ 4,110	$ (7,413)
Amount of loss reclassified from accumulated other comprehensive income into interest expense	(7,445)	(5,615)	(4,117)
Amount of gain reclassified from accumulated other comprehensive income into non-cash expense on interest rate swap included in discontinued operations	0	0	215
Amount of loss recognized in income on derivative (ineffective portion, reclassifications of missed forecasted transactions and amounts excluded from effectiveness testing)	$ (212)	$ (390)	$ 0