Schedule IV Mortgage Loans Receivable on Real Estate - Changes in Mortgage Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Mortgage Loans On Real Estate [Abstract]
Balance at beginning of period	$ 18,635		$ 10,000		$ 10,000
Additions during year:
New mortgage loans	34,092	[1]	21,135	[2]
Mortgage loans on real estate period increase	34,092		21,135
Deductions during year:
Collection of principal	(1,349)
Foreclosure of mortgage note					0
Conversion to fee simple ownership	(6,384)	[1]	(12,500)	[2]
Mortgage loans on real estate period decrease	(7,733)		(12,500)
Balance at end of period	$ 44,994	[3]	$ 18,635		$ 10,000

[1] On September 27, 2018, the Company acquired the newly constructed Norris Academy. The purchase price of approximately $6.4 million was satisfied by applying the aggregate principal amount outstanding on the construction mortgage loan provided by the Company. The Company funded approximately $1.9 million on the construction mortgage loan for the year ended December 31, 2017 and approximately $4.5 million for the year ended December 31, 2018.

[2] On January 30, 2017, the Company invested $12.5 million through a newly originated interest-only loan secured by a first mortgage on a licensed general acute care surgical hospital. On November 10, 2017, the Company completed the acquisition of Advanced Diagnostics Hospital East for a purchase price of $17.5 million, pursuant to the exercise of its exclusive right to purchase the property contained in the Company's $12.5 million mortgage note receivable. The $12.5 million in principal outstanding on the mortgage note receivable was applied to the purchase price, and the Company paid an additional $5.0 million in cash in satisfaction of the purchase price.

[3] Carrying amount of mortgages represents the contractual amount due under the mortgage note as of the date of this Schedule IV and excludes any other fees or costs associated with the mortgage notes and their origination. The aggregate cost for federal income tax purposes as of December 31, 2018 is estimated to be $45.0 million.