Segment Reporting Summary Of Information Of Long-Lived Assets In Different Geographic Areas (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	$ 508,855	$ 551,163
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	191,502	209,634
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	151,288	158,950
Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	6,100	8,787
France
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	69,558	76,535
Spain
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	87,614	93,049
South Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	2,547	2,879
Italy
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	10	1,032
Switzerland
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	192	266
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Net property, plant and equipment	[1]	$ 44	$ 31

[1] Long-lived assets represent fixed assets, net of accumulated depreciation.