EQUITY - Changes in common stock (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Equity
Beginning common shares outstanding	86,793,521	86,149,720
Common stock issued	6,151,514	0
Common Unit redemptions	119,308	268,947
Forfeitures	(1,420)	(46,030)
Shares retained for employee tax withholding requirements	(61,622)	(36,385)
Ending common shares outstanding	93,525,469	86,793,521
Equity Plan
Equity
Grants under the Equity Plan	446,686	320,845
Exercise of stock options	37,684	99,738
Outside directors
Equity
Grants under the Equity Plan	32,180	30,440
Common stock issued for director fees	7,618	6,246