Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Jan. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Assets Acquired:
Cash	$ 6,511	$ 1,529	$ 4,975	$ 4,273	$ 3,089
Receivables	51,670	5,002	41,168
Inventories	61,079	7,602	49,436
Prepaid expenses and other current assets	3,431	172	2,266
Current deferred income taxes		466
Property, plant and equipment	68,191	3,774	66,102
Intangible assets	61,169	29,500	33,680
Goodwill	35,670	26,305	9,365
Total assets	297,943	74,350	218,910
Liabilities Assumed:
Payables	18,859	3,430	11,365
Accrued compensation and employee benefits	7,768	569	6,734
Income taxes		31
Long-term deferred income taxes	10,230	12,273
Other long-term liabilities	5,592	451	1,078
Total liabilities assumed		$ 16,754