SUBSEQUENT EVENTS SUBSEQUENT EVENTS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2015
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs	$ 0	$ 54,196	$ 19,886
Subsequent Event [Member]
Subsequent Event [Line Items]
Issuance of common stock, net of costs (in shares)				2,588,000
Share price of stock issued (in US$ per share)				$ 20.00
Proceeds from issuance of common stock, net of issuance costs				$ 48,200