Operations by Industry Segment and Geographic Area, External Customers and Long-Lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	$ 983,157	$ 975,595	$ 932,998
Long-lived assets by geographic region	170,206	187,610
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	722,287	654,230	599,054
Long-lived assets by geographic region	141,727	150,425
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	1,129	1,324
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	54,321	61,898	70,991
Long-lived assets by geographic region	2,987	3,592
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	4,351	5,111
Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	45,671	47,940	62,911
Australia and Oceana [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	29,995	34,772	47,505
South America (excluding Brazil) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	32,454	49,797	33,526
Post-Soviet States (excluding Russia) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	8,345	8,245	25,849
Russia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	8,466	25,589	17,440
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	6,990	9,993	15,917
Northern Ireland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	5,116	5,065
Other European Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	23,867	12,365	15,428
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	8,376	12,869	11,620
Long-lived assets by geographic region	9,780	14,798
Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	18,995	13,327	6,699
Other Asian Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	9,513	17,018	5,836
Central America (excluding Mexico) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	4,404	9,275	5,620
West Indies [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	1,532	4,478	5,294
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	1,330	7,451	3,857
India [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	2,706	1,743	3,672
Japan and Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	3,574	4,377	1,749
Other Foreign Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	331	228	30
Total Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total consolidated sales	260,870	321,365	$ 333,944
Long-lived assets by geographic region	28,479	37,185
South Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets by geographic region	$ 5,116	$ 7,295