Mortgage and Other Notes Receivable (Details) $ in Thousands			3 Months Ended
	Apr. 25, 2018 USD ($) hospital	Dec. 28, 2017 USD ($) real_estate_property	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) mortgage_note_receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage note receivable, net						$ 10,600
Notes receivable			$ 24,119		$ 24,110
Proceeds from the repayment of notes receivable			31	$ 17
Repayments of mortgage note payable	$ 6,700		27	0
Real estate property			$ 417,874		389,632
Mortgage Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of mortgage note receivables | mortgage_note_receivable						1
Promissory Notes, Secured by Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans on real estate, face amount of mortgages		$ 11,450
Notes receivable		8,750
Receivable with imputed interest, discount		2,700
Promissory Notes, Secured By Facilities Owned By Borrower [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable	23,000			$ 2,200
Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable					$ 900
Proceeds from the repayment of notes receivable		$ 10,950
Proceeds from the repayment of notes receivable, interest	260
Proceeds from the repayment of notes receivable, fees and expenses	$ 250
Other Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest receivable						$ 600
Long-Term Acute Care Facility [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties used to secure notes by borrower | hospital	7
Inpatient Rehabilitation Hospital [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties used to secure notes by borrower | hospital	1
Specialty Hospital [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties used to secure notes by borrower | real_estate_property		2
Property Previously Financed By Mortgage Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate property	$ 4,500