EQUITY STRUCTURE AND ACCOUNTS - Schedule of repurchase of treasury stock activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Treasury Stock [Roll Forward]
Repurchases paid	$ (637)
2014 Share Repurchase Authorization Program
Treasury Stock [Roll Forward]
Remaining amount available for repurchase	$ 41,100
2014 Share Repurchase Authorization Program | Class A Common Stock
Class of Stock [Line Items]
Purchase of treasury stock (in shares)	40,065	0
Treasury Stock [Roll Forward]
Remaining amount available for repurchase	$ 41,769	$ 41,769
Additional authorizations	0
Repurchases paid	(637)	0
Repurchases unsettled	0	0
Remaining amount available for repurchase	$ 41,132	$ 41,769