Credit Concentration - Top Five Tenant Credit Concentrations (Details) - Sales Revenue, Services, Net $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Concentration Risk [Line Items]
Total ABR	$ 285,670
Percent of ABR	100.00%
CHI - Nebraska | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 15,906
Percent of ABR	5.60%
CHI - KentuckyOne Health | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 13,120
Percent of ABR	4.60%
Baylor Scott and White Health | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 7,402
Percent of ABR	2.60%
US Oncology | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 6,706
Percent of ABR	2.40%
US Oncology | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 6,239
Percent of ABR	2.20%
Remaining portfolio | Customer Concentration Risk
Concentration Risk [Line Items]
Total ABR	$ 236,297
Percent of ABR	82.60%