Reporting Segments Reporting segment asset data (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets:
Total assets	$ 400,705	$ 392,516	$ 398,511
GETS [Member]
Assets:
Total assets	144,055	130,730	135,179
PSS [Member]
Assets:
Total assets	150,318	162,835	163,727
MRI [Member]
Assets:
Total assets	26,723	28,697	26,698
Corporate [Member]
Assets:
Total assets	$ 79,609	$ 70,254	$ 72,907