SEGMENT INFORMATION (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011
SEGMENT INFORMATION
Number of operating segments									1
Segment information
Revenues derived from foreign subsidiaries	$ 23,969,000	$ 24,316,000	$ 26,836,000	$ 26,847,000	$ 28,024,000	$ 27,331,000	$ 28,862,000	$ 26,724,000	$ 101,968,000	$ 110,941,000
Identifiable assets	60,967,000				58,687,000				60,967,000	58,687,000
Sales to customers outside of the United States									44,761,000	51,611,000
Wholly owned foreign subsidiaries
Segment information
Revenues derived from foreign subsidiaries									42,172,000	47,757,000
Identifiable assets	$ 26,525,000				$ 25,484,000				$ 26,525,000	$ 25,484,000