Reporting Segments Total depreciation and amortization by reporting segment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 10,265	$ 11,008	$ 10,657
GETS [Member]
Segment Reporting Information [Line Items]
Total depreciation and amortization	5,171	5,761	5,265
PSS [Member]
Segment Reporting Information [Line Items]
Total depreciation and amortization	840	1,210	1,281
MRI [Member]
Segment Reporting Information [Line Items]
Total depreciation and amortization	538	400	443
Corporate [Member]
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 3,716	$ 3,637	$ 3,668