Balance Sheet Details (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts receivable:
Accounts receivable	$ 92,950	$ 83,977
Allowances for accounts receivable	8,956	8,538
Inventories:
Finished goods	185,185	175,074
Work in process	1,746	1,363
Raw materials	3,608	4,026
Repair parts	10,279	10,116
Operating supplies	1,746	1,524
Total inventories, less loss provisions of $8,051 and $9,453	202,564	192,103
Inventory loss provisions	8,051	9,453
Accrued liabilities:
Accrued incentives	22,740	19,359
Other accrued liabilities	25,277	24,369
Total accrued liabilities	48,017	43,728
Trade receivables
Accounts receivable:
Accounts receivable	90,850	82,521
Other receivables
Accounts receivable:
Accounts receivable	$ 2,100	$ 1,456