Balance Sheet Details (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts receivable:
Accounts receivable	$ 91,106	$ 94,549
Allowance for doubtful accounts	5,586	5,846
Inventories:
Finished goods	151,698	144,945
Work in process	1,153	1,615
Raw materials	4,708	4,558
Repair parts	10,840	10,550
Operating supplies	1,429	1,453
Total inventories, less loss provisions of $4,370 and $4,913	169,828	163,121
Inventory loss provision	4,370	4,913
Prepaid and other current assets
Value added tax	13,512	6,697
Prepaid expenses	6,947	8,396
Deferred income taxes	4,888	5,840
Prepaid income taxes	1,951	3,511
Derivative asset	403	394
Total prepaid and other current assets	27,701	24,838
Other assets:
Deposits	890	919
Finance fees — net of amortization	6,958	10,472
Other assets	6,128	2,143
Total other assets	13,976	13,534
Accrued liabilities:
Accrued incentives	17,648	17,830
Workers compensation	7,121	7,108
Medical liabilities	3,887	3,433
Interest	3,876	3,331
Commissions payable	1,068	1,067
Withholdings and other non-income tax accruals	3,078	1,929
Other accrued liabilities	5,960	6,720
Total accrued liabilities	42,638	41,418
Other long-term liabilities:
Deferred liability	8,081	7,424
Derivative liability	215	2,073
Environmental obligation (see note 18)	1,000	0
Other long-term liabilities	3,860	4,277
Total other long-term liabilities	13,156	13,774
Trade receivables [Member]
Accounts receivable:
Accounts receivable	87,700	87,499
Other receivables [Member]
Accounts receivable:
Accounts receivable	$ 3,406	$ 7,050