EQUITY STRUCTURE AND ACCOUNTS - Dividends Declared (Details) - $ / shares					3 Months Ended				12 Months Ended
	Dec. 10, 2015	Sep. 10, 2015	Jun. 15, 2015	Apr. 06, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Dividends per share of common stock (in dollars per share)					$ 1.45	$ 0.275	$ 0.25	$ 0.25
Class A common stock
Class of Stock [Line Items]
Dividends per share of common stock (in dollars per share)	$ 1.45	$ 0.275	$ 0.25	$ 0.25					$ 2.225	$ 0