Financial Commitments (Long-Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total debt, net	$ 780,789	$ 759,519
Less - current maturities	(27,598)	(85,890)
Long-term debt, net	753,191	673,629
2010 Senior Notes [Member]
Debt Instrument [Line Items]
Total debt, net	298,374	298,120
Term Loan [Member]
Debt Instrument [Line Items]
Total debt, net	47,699	54,650
Convertible Notes [Member]
Debt Instrument [Line Items]
Total debt, net	154,832	152,668
Equipment Financing, Mortgages And Acquisition-Related Notes [Member]
Debt Instrument [Line Items]
Total debt, net	95,453	101,558
Other Indebtedness [Member]
Debt Instrument [Line Items]
Total debt, net	3,129	4,533
2014 Revolver [Member]
Debt Instrument [Line Items]
Total debt, net	$ 181,302	$ 147,990