Segment Information (Long-Lived Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated long-lived assets	$ 234,549	$ 186,834	$ 155,100
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	133,176	119,981	111,567
Belgium [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	64,051	43,547	30,679
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	19,319	9,276	6,050
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	9,152	7,789
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	8,043	4,427	5,044
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	653	1,642	1,723
Singapore [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	135	148	6
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 20	$ 24	$ 31