COMMON STOCK Stockholders' Equity Note (Details) - USD ($)		3 Months Ended
	Aug. 19, 2013	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share			$ 0.01	$ 0.01
Common Stock, Value, Issued			$ 402,000	$ 359,000
Additional paid-in capital			$ 907,382,000	$ 689,209,000
March 2015 Common Stock Issuance
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		4,002,000
Common Stock, Par or Stated Value Per Share		$ 0.01
Sale of Stock, Price Per Share		$ 50.73
Proceeds from Issuance of Common Stock		$ 202,900,000
Common Stock, Value, Issued		40,020
Additional paid-in capital		$ 202,800,000
August 2013 Common Stock Issuance
Class of Stock [Line Items]
Stock Issuance Date	Aug. 19, 2013
Stock Issued During Period, Shares, New Issues	5,175,000
Common Stock, Par or Stated Value Per Share	$ 0.01
Sale of Stock, Price Per Share	$ 53.37
Proceeds from Issuance of Common Stock	$ 275,800,000
Common Stock, Value, Issued	51,750
Additional paid-in capital	$ 275,800,000