Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 segment	Jun. 30, 2011	Dec. 31, 2011
Segment Information
Number of operating segments			1
Segment information
Revenues	$ 26,836,000	$ 28,862,000	$ 53,683,000	$ 55,586,000
Identifiable assets	58,712,000		58,712,000		58,687,000
Wholly owned foreign subsidiaries
Segment information
Revenues	11,482,000	12,467,000	22,314,000	25,011,000
Identifiable assets	24,739,000	25,637,000	24,739,000	25,637,000
All subsidiaries
Segment information
Sales to customers outside of the United States	$ 11,403,000	$ 13,383,000	$ 23,733,000	$ 26,837,000