CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Securities held as collateral, at fair value	$ 60.5	$ 59.9
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	19,254,141	14,429,055
Common stock, shares outstanding	19,254,141	14,429,055
Series A Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	300,000	300,000
Preferred stock, dividend rate	7.00%	7.00%
Preferred stock, shares issued	110,000	40,000
Preferred stock, shares outstanding	110,000	40,000
Preferred stock, liquidation preference value	$ 110.0	$ 40.0
Series B Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,750,000	3,750,000
Preferred stock, dividend rate	7.00%	7.00%
Preferred stock, shares issued	1,571,734	0
Preferred stock, shares outstanding	1,571,734	0
Preferred stock, liquidation preference value	$ 39.3	$ 0.0
Bridge Loan Investments [Member]
Loans pledged as collateral	78.6
Operating Property Loans [Member]
Loans pledged as collateral	$ 6.0	$ 6.0