Operations by Industry Segment and Geographic Area, External Customers and Long-Lived Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	$ 975,595	$ 932,998	$ 936,273
Long-lived assets by geographic region	187,610	184,520
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	654,230	599,054	572,522
Long-lived assets by geographic region	150,425	156,927
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	1,324	1,541
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	61,898	70,991	79,554
Long-lived assets by geographic region	3,592	4,145
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	5,111	5,680
Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	47,940	62,911	60,811
Australia and Oceana [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	34,772	47,505	62,683
South America (excluding Brazil) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	49,797	33,526	38,049
Post-Soviet States (excluding Russia) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	8,245	25,849	11,533
Russia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	25,589	17,440	14,641
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	9,993	15,917	23,084
Northern Ireland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	5,065	0
Other European Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	12,365	15,428	20,249
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	12,869	11,620	15,675
Long-lived assets by geographic region	14,798	9,024
Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	13,327	6,699	6,705
Other Asian Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	17,018	5,836	8,315
Central America (excluding Mexico) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	9,275	5,620	6,843
West Indies [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	4,478	5,294	2,765
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	7,451	3,857	6,687
India [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	1,743	3,672	4,648
Japan and Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	4,377	1,749	1,509
Other Foreign Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	228	30	0
Total Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	321,365	333,944	363,751
Long-lived assets by geographic region	37,185	27,593
South Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	$ 7,295	$ 7,203