EQUITY STRUCTURE AND ACCOUNTS - Dividends Declared (Details) - $ / shares					3 Months Ended		6 Months Ended
	May 30, 2019	Feb. 27, 2019	May 30, 2018	Feb. 27, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Class A Common Stock
Class of Stock [Line Items]
Dividends per share of Class A common stock (in dollars per share)	$ 0.340	$ 0.340	$ 0.325	$ 0.315	$ 0.340	$ 0.325	$ 0.680	$ 0.640