Credit Concentration - Schedule of ABR (Annualized Base Rent) (Details) - Sales Revenue, Services, Net $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($) Rate
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 281,290
Percent of ABR (annualized base rent) | Rate	100.00%
Customer Concentration Risk | CHI - Nebraska
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 16,336
Percent of ABR (annualized base rent)	5.80%
Customer Concentration Risk | CHI - KentuckyOne Health
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 13,574
Percent of ABR (annualized base rent)	4.80%
Customer Concentration Risk | Northside Hospital
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 9,860
Percent of ABR (annualized base rent)	3.50%
Customer Concentration Risk | Baylor Scott and White Health
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 7,583
Percent of ABR (annualized base rent)	2.70%
Customer Concentration Risk | Ascension - St. Vincent's - Indianapolis
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 7,271
Percent of ABR (annualized base rent)	2.60%
Customer Concentration Risk | Remaining portfolio
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 226,666
Percent of ABR (annualized base rent) | Rate	80.60%
Geographic Concentration Risk | Texas
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 42,458
Percent of ABR (annualized base rent)	15.10%
Geographic Concentration Risk | Georgia
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 24,372
Percent of ABR (annualized base rent)	8.70%
Geographic Concentration Risk | Indiana
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 19,749
Percent of ABR (annualized base rent)	7.00%
Geographic Concentration Risk | Nebraska
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 17,734
Percent of ABR (annualized base rent)	6.30%
Geographic Concentration Risk | Minnesota
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 16,858
Percent of ABR (annualized base rent)	6.00%
Geographic Concentration Risk | Other
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 160,119
Percent of ABR (annualized base rent)	56.90%