Real Estate Investments - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) mortgage_note_receivable real_estate_property	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Real Estate [Abstract]
Straight-line rent	$ 1,303	$ 606	$ 133
Value of real estate property investments and mortgages	$ 399,119
Number of real estate properties | real_estate_property	86
Number of mortgage note receivables | mortgage_note_receivable	1
Depreciation	$ 7,600	$ 4,500	$ 1,500