Financial Commitments (Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total debt	$ 759,519	$ 817,684
Less - current maturities	(85,890)	(88,917)
Long-term debt, net	673,629	728,767
Term Loan [Member]
Debt Instrument [Line Items]
Total debt	54,650	222,120
2010 Notes [Member]
Debt Instrument [Line Items]
Total debt	298,120	297,118
Convertible Notes [Member]
Debt Instrument [Line Items]
Total debt	152,668
Equipment Financing And Mortgages [Member]
Debt Instrument [Line Items]
Total debt	101,558	133,288
Other Indebtedness [Member]
Debt Instrument [Line Items]
Total debt	4,533	9,343
2014 Revolver [Member]
Debt Instrument [Line Items]
Total debt	$ 147,990	$ 155,815