EARNINGS PER SHARE (Details)	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation between basic and diluted earnings per share
Weighted average number of common shares outstanding (in shares)	32,071,202	32,000,000	31,799,536	31,700,000	31,500,000	32,024,603	31,671,781	31,700,000	31,200,000	30,800,000
Dilutive impact of stock based compensation	381,676		393,922			315,636	455,777
Weighted average number of common and common equivalent shares outstanding for the period	32,452,878	32,300,000	32,193,458	32,200,000	32,000,000	32,340,239	32,127,558	32,100,000	31,500,000	31,000,000
Number of common shares outstanding at the end of the period	31,959,139		31,666,904			31,959,139	31,666,904
Weighted average anti-dilutive shares excluded from the computation of diluted earnings per share	276,753		218,800			635,738	186,929