Guarantees, Other Contingent Liabilities, And Other Matters (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Jan. 09, 2017
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Face amount of guarantee including unpaid accrued interest	$ 36,000	$ 35,000	$ 17,000
Fair value of the guarantees	1,149	1,844	1,177
Other contingent liabilities	2,000
Net provision for losses (recoveries) on advances and guaranteed loans to suppliers	4,375	414
Dividends paid on convertible perpetual preferred stock	0	11,061
Repurchase of stock, retained earnings	(9,849)	$ 0
Series B 6.75% Convertible Perpetual Preferred Stock [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Preferred stock, shares converted to common stock		111,072
Percentage of outstanding convertible perpetual preferred stock converted		50.80%
Non-cash reclassification of preferred stock converted		$ 107,600
Preferred stock, shares outstanding				107,418
Payments for repurchase of convertible perpetual preferred stock			178,400
Dividends paid on convertible perpetual preferred stock			15,000
Repurchase of stock, retained earnings			74,400
Common Stock [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Conversion of Stock, Shares Issued		2,487,118
Advances to suppliers [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Advances to suppliers current and non-current	136,000	$ 125,000	134,000
Valuation Allowances and Reserves, Balance	24,000	30,000	27,000
Recoverable value added tax credits [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Aggregate balance of recoverable value added tax credits	52,000	41,000	45,000
Valuation Allowances and Reserves, Balance	17,000	$ 11,000	$ 13,000
Santa Catarina [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Brazil audit assessment for tax, penalties, and interest on recoverable value added tax credits	15,000
Reduced Brazil audit assessment for tax, penalties, and interest on recoverable value added tax credits	15,000
Santa Catarina [Member] | Minimum [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Estimate of possible loss on remaining VAT audit assessment	0
Santa Catarina [Member] | Maximum [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Estimate of possible loss on remaining VAT audit assessment	15,000
Parana [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Brazil audit assessment for tax, penalties, and interest on recoverable value added tax credits	17,000
Reduced Brazil audit assessment for tax, penalties, and interest on recoverable value added tax credits	5,000
Parana [Member] | Minimum [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Estimate of possible loss on remaining VAT audit assessment	0
Parana [Member] | Maximum [Member]
Guarantees, Other Contingent Liabilities, and Other Matters [Line Items]
Estimate of possible loss on remaining VAT audit assessment	$ 5,000