COMMON STOCK AND EARNINGS PER SHARE (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
COMMON STOCK AND EARNINGS PER SHARE
Weighted-average shares of common stock outstanding - basic	46,833,216	46,496,144
Potentially dilutive shares resulting from stock plans	739,000	600,000
Weighted average common shares - diluted	47,572,486	47,095,990
Antidilutive options not included in the weighted average common shares-diluted	164,000	262,000
Earnings per share, other disclosures
Purchase of common stock for treasury	$ (2,331,000)	$ (2,490,000)
Repurchase of common stock, shares	133,767	155,991
Exercise of stock options	$ 2,100,000	$ 400,000
Exercise of stock options, shares	183,036	37,089
Vested (in shares)	66,630	368,010