SUBSEQUENT EVENTS (Details) - $ / shares			12 Months Ended
	Mar. 04, 2016	Feb. 08, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsequent event
Subsequent Events
Special dividend declared (in dollars per share)		$ 0.80
Dividends declared per share		$ 0.30
Class A common stock
Subsequent Events
Dividends declared per share			$ 1.00	$ 1.40
Class A common stock | Subsequent event
Subsequent Events
Dividends declared per share	$ 1.10