Subsequent events (Details) $ / shares in Units, $ in Millions			1 Months Ended	2 Months Ended	3 Months Ended			10 Months Ended	12 Months Ended
	May 08, 2020 USD ($) item loan	Apr. 13, 2020 $ / shares	May 08, 2020 USD ($) loan	Dec. 31, 2019	Mar. 31, 2020 USD ($) loan	Mar. 31, 2019	[1]	Nov. 14, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Financial Designation, Predecessor and Successor [Fixed List]				Successor	Successor	Predecessor		Predecessor	Predecessor
Impaired Financing Receivable, Number Of Loans | loan					4
Impaired Financing Receivable, Unpaid Principal Balance					$ 31.7
Subsequent Event
Subsequent Event [Line Items]
Common stock dividend declared | $ / shares		$ 0.06
Number of Mortgage notes receivable originated and/or refinanced | item	6
Financing Receivable, Loan in Process	$ 6.0		$ 6.0
Impaired Financing Receivable, Number Of Loans | loan	5		5
Impaired Financing Receivable, Unpaid Principal Balance	$ 50.5		$ 50.5
Impaired Financing Receivable, Number Of Loans Cured | loan			6
Impaired Financing Receivable, Cured Unpaid Principal Balance			$ 4.1

[1] Predecessor periods are combined as disclosed in Note 1.