EQUITY - Narrative (Details) - USD ($)					12 Months Ended
	Oct. 02, 2017	Sep. 28, 2017	Aug. 17, 2017	Mar. 21, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Shares of preferred stock issued (in shares)				5,800,000	5,750,000	5,750,000
Preferred stock dividend rate				7.125%
Redemption price per share (in dollars per share)				$ 25.00
Net proceeds from issuance of preferred stock				$ 138,300,000	$ 0
Preferred stock dividends in arrears					$ 0
Convertible preferred stock conversion price (in dollars per share)				$ 25.00
Number of shares issued upon conversion of convertible preferred stock (in shares)				1.7864
Vesting of common stock units (in shares)					300,000	100,000
Tax withholding obligations					$ 3,100,000	$ 1,500,000	$ 5,000,000
Public Stock Offering
Class of Stock [Line Items]
Shares of common stock issued (in shares)	18,400,000	16,000,000
Consideration received	$ 370,900,000
Common stock share price (in dollars per share)	$ 21.00
Over-Allotment Option
Class of Stock [Line Items]
Shares of common stock issued (in shares)	2,400,000
Care Capital Properties
Class of Stock [Line Items]
Shares of common stock issued in merger (in shares)			94,000,000