Investment Activity - Schedule of Tenant Concentration of Revenue (Details) - Credit Concentration Risk - Sales Revenue, Net	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Baylor Scott & White Health
Concentration Risk [Line Items]
Concentration risk percentage	25.60%		24.10%		[1]
Fundamental Healthcare
Concentration Risk [Line Items]
Concentration risk percentage	17.20%		15.10%	16.70%
Vibra Healthcare
Concentration Risk [Line Items]
Concentration risk percentage	15.80%		12.90%	15.50%
Life Generations Healthcare
Concentration Risk [Line Items]
Concentration risk percentage	15.00%		14.10%	17.50%
Prior Texas Ten Tenant
Concentration Risk [Line Items]
Concentration risk percentage		[2]	23.50%	28.90%

[1] Percentage of revenue is less than 10%.

[2] The Company began recognizing revenue under the master lease as cash is received from the Prior Texas Ten Tenant effective July 1, 2018. As a result, the percentage of revenue for the year ended December 31, 2018 is less than 10%. On December 31, 2018, the lease with the Prior Texas Ten Tenant was terminated. The Company entered into a 15-year triple-net master lease agreement with certain affiliates of Creative Solutions for the Texas Ten Portfolio, which commenced on January 1, 2019. See “Texas Ten Portfolio Master Lease Update” above.