STOCKHOLDERS' EQUITY - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013	Jan. 31, 2019
Class Of Stock [Line Items]
Shares repurchased during period	10,653,000	397,000	0
Redeemable preferred stock, face value	$ 250,946	$ 250,946
Proceeds from issuance of preferred shares		$ 52,051	$ 1,898
Cumulative Redeemable Preferred Stock, Series E [Member]
Class Of Stock [Line Items]
Redeemable preferred stock, shares issued (in shares)	10,329,000	10,329,000		6,800,000
Redeemable preferred stock, face value				$ 170,000
Preferred stock, dividend rate	7.50%	7.50%		7.50%
Redeemable preferred stock, liquidation preference per share (in dollars per share)				$ 25.00
Cumulative Redeemable Preferred Stock, Series E [Member] | Continuous Offering Program [Member]
Class Of Stock [Line Items]
Shares	0	2,100,000	78,000
Net Issue Price		$ 24.77	$ 24.23
Proceeds from issuance of preferred shares		$ 51,900	$ 1,900
Directors And Employees [Member]
Class Of Stock [Line Items]
Additions to common equity capital related to equity-based awards	$ 1,700	$ 1,100	$ 1,400
Subsequent Event [Member]
Class Of Stock [Line Items]
Common stock repurchase program					$ 125,000
Stock remaining repurchase program authorized amount					$ 37,000