Balance Sheet Details (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable:
Accounts receivable	$ 94,379	$ 91,106
Accounts receivable allowances	7,066	5,586
Inventories:
Finished goods	159,998	151,698
Work in process	1,183	1,153
Raw materials	4,944	4,708
Repair parts	10,763	10,840
Operating supplies	1,139	1,429
Total inventories, less loss provisions of $5,313 and $4,370	178,027	169,828
Inventory loss provision	5,313	4,370
Prepaid and other current assets
Value added tax	11,467	13,512
Prepaid expenses	6,310	6,947
Deferred income taxes	0	4,888
Prepaid income taxes	1,304	1,951
Derivative asset	245	403
Total prepaid and other current assets	19,326	27,701
Accrued liabilities:
Accrued incentives	21,450	17,648
Workers compensation	6,700	7,121
Medical liabilities	4,002	3,887
Interest	3,808	3,876
Commissions payable	776	1,068
Withholdings and other non-income tax accruals	2,184	3,078
Other accrued liabilities	6,259	5,960
Total accrued liabilities	45,179	42,638
Other long-term liabilities:
Deferred liability	7,131	8,081
Derivative liability	315	215
Environmental obligation (see note 18)	1,085	1,000
Other long-term liabilities	2,655	3,860
Total other long-term liabilities	11,186	13,156
Trade receivables [Member]
Accounts receivable:
Accounts receivable	91,324	87,700
Other receivables [Member]
Accounts receivable:
Accounts receivable	$ 3,055	$ 3,406