Credit Concentration - Schedule of ABR (Annualized Base Rent) (Details) - Sales Revenue, Services, Net $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) Rate
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 277,705
Percent of ABR (annualized base rent) | Rate	100.00%
Customer Concentration Risk | CHI - Nebraska
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 16,244
Percent of ABR (annualized base rent)	5.90%
Customer Concentration Risk | CHI - KentuckyOne Health
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 13,484
Percent of ABR (annualized base rent)	4.90%
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 | US Oncology
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 6,785
Percent of ABR (annualized base rent)	2.40%
Customer Concentration Risk | CHI - St. Alexius (ND)
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 6,391
Percent of ABR (annualized base rent)	2.30%
Customer Concentration Risk | Remaining portfolio
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 227,218
Percent of ABR (annualized base rent) | Rate	81.80%
Geographic Concentration Risk | Texas
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 47,019
Percent of ABR (annualized base rent)	16.90%
Geographic Concentration Risk | Georgia
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 20,517
Percent of ABR (annualized base rent)	7.40%
Geographic Concentration Risk | NEBRASKA
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 17,662
Percent of ABR (annualized base rent)	6.40%
Geographic Concentration Risk | Indiana
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 16,993
Percent of ABR (annualized base rent)	6.10%
Geographic Concentration Risk | Minnesota
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 16,798
Percent of ABR (annualized base rent)	6.10%
Geographic Concentration Risk | Other
Concentration Risk [Line Items]
Total ABR (annualized base rent)	$ 158,716
Percent of ABR (annualized base rent)	57.10%