SUBSEQUENT EVENTS - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands												3 Months Ended								12 Months Ended
	Dec. 10, 2015	Sep. 18, 2015	May. 14, 2015	Mar. 16, 2015	Dec. 18, 2014	Sep. 18, 2014	Jun. 17, 2014	Mar. 19, 2014	Dec. 17, 2013	Sep. 18, 2013	Jun. 03, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Dividend declared per share (in dollars per share)	$ 0.46	$ 0.46	$ 0.45	$ 0.38	$ 0.38	$ 0.35	$ 0.5	$ 0.35	$ 0.5	$ 0.35	$ 0.14	$ 0.46	$ 0.46	$ 0.45	$ 0.38	$ 0.38	$ 0.35	$ 0.5	$ 0.35	$ 1.75	$ 1.58	$ 0.99
Dividends	$ 106,000	$ 106,000	$ 89,500	$ 53,700	$ 53,700	$ 49,500	$ 70,600	$ 44,300	$ 63,300	$ 44,300	$ 17,700									$ 355,295	$ 218,094	$ 125,317