Debt (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013
Schedule of Debt Instruments [Line Items]
Industrial revenue bonds	$ 7,815		$ 7,815
TOTAL	254,611		262,946
Industrial revenue bonds due 2028 [Member] | Short-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Instrument, Unamortized Discount	0	[1]	0	[1]
Debt Instrument, Maturity Date	Apr. 01, 2028	[1]	Apr. 01, 2028	[1]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	12.00%	[1]	12.00%	[1]
Industrial revenue bonds	7,815	[1]	7,815	[1]
Debt Instrument, Interest Rate, Stated Percentage	0.24%	[1]
Senior unsecured notes due August 15, 2014 [Member] | Short-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Instrument, Unamortized Discount	0	[2],[3]	0	[2],[3]
Debt Instrument, Maturity Date	Aug. 15, 2014	[2],[3]	Aug. 15, 2014	[2],[3]
Senior unsecured notes, current	0	[2],[3]	2,603	[2],[3]
Debt Instrument, Interest Rate, Stated Percentage	7.50%	[2],[3]	7.50%	[2],[3]
Iceland revolving line of credit [Member] | Short-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Revolving credit facility	0	[3],[4]	6,000	[3],[4]
Debt Instrument, Interest Rate, Stated Percentage			3.92%	[3],[4]
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Instrument, Unamortized Discount	3,204		3,472
Debt Instrument, Maturity Date	Jun. 01, 2021		Jun. 01, 2021
Senior secured notes, noncurrent	$ 246,796		$ 246,528
Debt Instrument, Interest Rate, Stated Percentage	7.50%		7.50%

[1] The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The IRB interest rate at September 30, 2014 was 0.24%.

[2] The amount outstanding was repaid upon maturity.

[3] These items are recorded in accrued and other current liabilities based on the repayment terms and expected maturity.

[4] Borrowings under the Iceland revolving credit facility bear variable interest based on LIBOR plus the applicable margin per annum. The interest rate at December 31, 2013 was 3.92%.