Assets Held for Sale and Discontinued Operations, Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations, net of tax	$ 765	$ 643	$ 1,832	$ 2,447
Zambian Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales	14,645	13,361	35,294	40,550
Other income (loss), net	26	(28)	54	22
Cost of products sold	12,007	10,570	28,158	31,466
Selling, general and administrative	1,637	1,922	4,796	5,822
Currency exchange losses (gains), net	6	(102)	(63)	(303)
Income from discontinued operations before income taxes	1,021	943	2,457	3,587
Provision for income taxes	256	300	625	1,140
Income from discontinued operations, net of tax	$ 765	$ 643	$ 1,832	$ 2,447