DIVIDENDS AND DISTRIBUTIONS (Details) - USD ($) $ / shares in Units, $ in Thousands													12 Months Ended
	Nov. 08, 2019	Jul. 26, 2019	May 01, 2019	Feb. 21, 2019	Oct. 30, 2018	Jul. 26, 2018	May 01, 2018	Mar. 01, 2018	Nov. 01, 2017	Aug. 03, 2017	May 02, 2017	Mar. 07, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
DIVIDENDS AND DISTRIBUTIONS
Dividends per share amount paid (in dollars per share)	$ 0.33	$ 0.33	$ 0.33	$ 0.33	$ 0.31	$ 0.29	$ 0.28	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 1.32	$ 1.16	$ 1.08
Total cash dividends	$ 9,546	$ 9,526	$ 9,527	$ 9,520	$ 8,914	$ 8,323	$ 8,036	$ 8,008	$ 7,722	$ 7,717	$ 7,718	$ 7,690	$ 38,119	$ 33,281	$ 30,847