Reporting Segments Capital expenditure data by reporting segment (Details) (USD $)	12 Months Ended																				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 GETS [Member]		Dec. 31, 2011 GETS [Member]		Dec. 31, 2010 GETS [Member]		Dec. 31, 2012 PSS [Member]	Dec. 31, 2011 PSS [Member]	Dec. 31, 2010 PSS [Member]	Dec. 31, 2012 MRI [Member]	Dec. 31, 2011 MRI [Member]	Dec. 31, 2010 MRI [Member]	Dec. 31, 2012 Corporate [Member]	Dec. 31, 2011 Corporate [Member]	Dec. 31, 2010 Corporate [Member]	Dec. 31, 2010 L.R. Kimball [Member] GETS [Member]	Dec. 20, 2010 DSPCon, Inc [Member] GETS [Member]	Dec. 31, 2010 Including L R Kimball and DSPCon Property and Equipment Acquired [Member]
Segment Reporting Information [Line Items]
Total purchases of property and equipment	$ 6,225,000	$ 5,658,000	$ 5,890,000	$ 4,082,000	[1]	$ 2,734,000	[1]	$ 8,473,000	[1]	$ 837,000	$ 757,000	$ 538,000	$ 116,000	$ 649,000	$ 312,000	$ 1,190,000	$ 1,518,000	$ 2,526,000			$ 11,849,000
Property, plant, and equipment acquired in business acquisition																			$ 5,700,000	$ 300,000

[1] GETS purchases of property and equipment in 2010 include $5.7 million and $0.3 million of property and equipment purchases in the acquisitions of L.R. Kimball and DSPCon, respectively.