EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2012
Weighted average number diluted shares outstanding adjustment [Abstract]
Restricted stock awards that contain non-forfeitable rights to dividends (in shares)																	45
Basic and Diluted Shares Outstanding [Abstract]
Weighted average shares outstanding-basic (in shares)																	7,927		7,810		8,002
Effect of dilutive shares (in shares)																	72		93		93
Weighted average shares outstanding-diluted (in shares)																	7,999		7,903		8,095
Calculation of earnings per share - basic [Abstract]
Net earnings	$ 8,222		$ 10,610		$ 8,591		$ 7,850		$ 7,702		$ 9,033		$ 10,033		$ 8,062		$ 35,273		$ 34,830		$ 23,367
Net earnings attributable to participating securities																	307		668		764
Net earnings attributable to common share holders																	34,966		34,162		22,603
Earnings per share - basic (in dollars per share)	$ 1.04	[1]	$ 1.33	[1]	$ 1.07	[1]	$ 0.98	[1]	$ 0.96	[1]	$ 1.11	[1]	$ 1.26	[1]	$ 1.01	[1]	$ 4.41		$ 4.37	[1]	$ 2.82
Calculation of earnings per share - diluted [Abstract]
Net earnings attributable to common shareholders- basic																	34,966		34,162		22,603
Add: undistributed earnings attributable to participating securities																	3		4		9
Net earnings attributable to common shareholders- diluted																	$ 34,969		$ 34,166		$ 22,612
Earnings per share - diluted (in dollars per share)	$ 1.03	[1]	$ 1.32	[1]	$ 1.06	[1]	$ 0.97	[1]	$ 0.95	[1]	$ 1.11	[1]	$ 1.25	[1]	$ 1.00	[1]	$ 4.37	[1]	$ 4.32	[1]	$ 2.79

[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.