Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2017

Balance Sheet Details [Abstract]

Schedule of Other Assets and Other Liabilities [Table Text Block]

The following table provides detail of selected balance sheet items:

December 31, (dollars in thousands)	2017		2016
Accounts receivable:
Trade receivables	$	88,786	$	82,851
Other receivables	1,211		2,262
Total accounts receivable, less allowances of $9,051 and $7,832	$	89,997	$	85,113
Inventories:
Finished goods	$	170,774	$	152,261
Work in process	1,485		1,625
Raw materials	3,906		4,432
Repair parts	10,240		10,558
Operating supplies	1,481		1,133
Total inventories, less loss provisions of $10,308 and $9,484	$	187,886	$	170,009
Accrued liabilities:
Accrued incentives	$	19,728	$	19,771
Other accrued liabilities	23,495		22,036
Total accrued liabilities	$	43,223	$	41,807