Balance Sheet Details (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable:
Accounts receivable	$ 89,084	$ 85,113
Allowance for doubtful accounts	7,176	7,832
Inventories:
Finished goods	183,212	152,261
Work in process	1,456	1,625
Raw materials	3,549	4,432
Repair parts	10,645	10,558
Operating supplies	1,319	1,133
Total inventories, less loss provisions of $10,727 and $9,484	200,181	170,009
Inventory loss provisions	10,727	9,484
Accrued liabilities:
Accrued incentives	24,674	19,771
Other accrued liabilities	24,837	22,036
Total accrued liabilities	49,511	41,807
Trade receivables
Accounts receivable:
Accounts receivable	87,315	82,851
Other receivables
Accounts receivable:
Accounts receivable	$ 1,769	$ 2,262