ACQUISITION OF MTGE INVESTMENT CORP - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended	6 Months Ended
	Sep. 07, 2018	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Preferred Stock, par value (in dollars per share)		$ 0.01	$ 0.01	$ 0.01
8.125% Series H Cumulative Redeemable Preferred Stock
Business Acquisition [Line Items]
Preferred stock dividend rate, percentage		8.125%	8.125%
Mountain Merger Sub Corporation | Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock dividend rate, percentage	8.125%
Preferred Stock, par value (in dollars per share)	$ 0.01
Mountain Merger Sub Corporation
Business Acquisition [Line Items]
Total consideration	$ 906,200
Equity issued	455,900
Cash	$ 450,287
Shares issued as part of the consideration for asset acquisition (in shares)	43.6
Mountain Merger Sub Corporation | 8.125% Series H Cumulative Redeemable Preferred Stock
Business Acquisition [Line Items]
Preferred Stock, par value (in dollars per share)	$ 0.01