EARNINGS PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2013		Mar. 31, 2012		Mar. 31, 2011
Weighted average number diluted shares outstanding adjustment [Abstract]
Weighted average decrease in the effect of dilutive shares (in shares)																			119,000		70,000
Decrease in basic earnings per share (in dollars per shares)																			$ 0.10		$ 0.06
Decrease in diluted earnings per share (in dollars per shares)																			$ 0.05		$ 0.04
Basic and Diluted Shares Outstanding [Abstract]
Weighted average shares outstanding-basic (in shares)																	7,809,938		8,002,191		8,200,577
Effect of dilutive shares (in shares)																	92,933		93,001		152,344
Weighted average shares outstanding-diluted (in shares)																	7,902,871		8,095,192		8,352,921
Calculation of Earnings Per Share - Basic [Abstract]
Net earnings	$ 7,702		$ 9,033		$ 10,033		$ 8,062		$ 3,857		$ 8,743		$ 7,064		$ 3,703		$ 34,830		$ 23,367		$ 23,727
Net earnings attributable to shareholders with participating rights																	668		764		524
Net earnings attributable to common share holders																	34,162		22,603		23,203
Net earnings per common share - Basic (in dollars per share)	$ 0.96	[1]	$ 1.11	[1]	$ 1.26	[1]	$ 1.01	[1]	$ 0.48	[1]	$ 1.08	[1]	$ 0.83	[1]	$ 0.43	[1]	$ 4.37	[1]	$ 2.82	[1]	$ 2.83
Calculation of Earnings Per Share - Diluted [Abstract]
Net earnings attributable to common share holders																	34,162		22,603		23,203
Add: undistributed earnings attributable to participating securities																	4		8		9
Net earnings attributable to common shareholders																	$ 34,166		$ 22,612		$ 23,213
Net earnings per common share - Diluted (in dollars per share)	$ 0.95	[1]	$ 1.11	[1]	$ 1.25	[1]	$ 1.00	[1]	$ 0.48	[1]	$ 1.07	[1]	$ 0.82	[1]	$ 0.43	[1]	$ 4.32	[1]	$ 2.79	[1]	$ 2.78

[1] Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share.