Segment Information (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment	Sep. 30, 2011	Dec. 31, 2011
Segment Information
Number of operating segments			1
Segment information
Revenues	$ 24,316,000	$ 27,331,000	$ 77,999,000	$ 82,917,000
Identifiable assets	59,461,000		59,461,000		58,687,000
Wholly owned foreign subsidiaries
Segment information
Revenues	9,771,000	11,263,000	32,085,000	36,274,000
Identifiable assets	25,335,000	26,022,000	25,335,000	26,022,000
All subsidiaries
Segment information
Sales to customers outside of the United States	$ 10,172,000	$ 11,989,000	$ 33,905,000	$ 38,826,000