COMMON STOCK ACTIVITY (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding at beginning of year (in shares)	33,332,213
Common stock offerings (in shares)	1,370,457	875,052	106,751
Stock Issued During Period, Value, New Issues	$ 109,207	$ 59,283	$ 6,233
Dividend reinvestment plan (in shares)	2,744	3,326	4,536
Shares outstanding at end of year (in shares)	34,758,167	33,332,213
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding at beginning of year (in shares)	33,332,213	32,421,460	32,232,587
Common stock offerings (in shares)	1,370,457	875,052	106,751
Dividend reinvestment plan (in shares)	2,744	3,326	4,536
Incentive restricted stock granted (in shares)	93,285	80,529	100,622
Incentive restricted stock forfeited (in shares)	(16,000)	(910)	0
Director common stock awarded (in shares)	8,881	10,072	9,373
Stock issued during period, restricted stock awarded to directors	282	0	0
Restricted stock withheld for tax obligations (in shares)	(33,695)	(57,316)	(32,409)
Shares outstanding at end of year (in shares)	34,758,167	33,332,213	32,421,460
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues	$ 109,207	$ 59,283	$ 6,233