COMMON STOCK Stockholders' Equity Note (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01
Common shares	$ 657		$ 659
Additional paid-in capital	$ 2,489,557		$ 2,503,294
March 2015 Common Stock Issuance
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		4,002,000
Sale of Stock, Price Per Share	$ 50.73
Proceeds from Issuance of Common Stock	$ 296,600	$ 202,900