Merger with Tremont Mortgage Trust - Narrative (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 30, 2021 USD ($) loan $ / shares	Dec. 31, 2021 USD ($)
Asset Acquisition [Line Items]
Purchase discount accretion		$ 18,932
TRMT Merger
Asset Acquisition [Line Items]
Number of loans acquired | loan	10
Aggregate principle loan balance acquired	$ 204,692
Share price (in dollars per share) | $ / shares	$ 10.31
Aggregate transaction value paid	$ 169,150
Assumed Citibank Master Repurchase Facility, principal balance	128,962
Merger related costs	6,160
Assumed working capital	(10,146)
Purchase discount	36,443
Purchase discount accretion		$ 18,932
TRMT Merger | Tremont Mortgage Trust And Seven Hills Realty Trust
Asset Acquisition [Line Items]
Merger related costs	$ 6,160