EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Net earnings attributable to common shareholders - basic and diluted	$ 13,246		$ 19,550		$ 20,098		$ 16,188		$ 15,052		$ 14,864		$ 18,003		$ 15,273		$ 69,082		$ 63,192		$ 55,122
Basic and diluted common shares outstanding [Abstract]
Weighted average common shares outstanding - basic (in shares)																	13,327		13,448		13,790
Effect of dilutive shares (in shares)																	88		130		177
Weighted average shares common outstanding - diluted (in shares)																	13,415		13,578		13,967
Earnings per common share - basic (in dollars per share)	$ 0.99	[1]	$ 1.47	[1]	$ 1.51	[1]	$ 1.21	[1]	$ 1.12	[1]	$ 1.10	[1]	$ 1.33	[1]	$ 1.14	[1]	$ 5.18	[1]	$ 4.70	[1]	$ 4.00
Earnings per common share - diluted (in dollars per share)	$ 0.99	[1]	$ 1.46	[1]	$ 1.51	[1]	$ 1.20	[1]	$ 1.12	[1]	$ 1.10	[1]	$ 1.33	[1]	$ 1.12	[1]	$ 5.15	[1]	$ 4.65	[1]	$ 3.95

[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.