Investments - Schedule of External Customers by Geographic Areas (Details) - Rental Revenue - Geographic Concentration Risk	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Texas
Concentration Risk [Line Items]
Concentration risk percentage	12.90%	12.20%	12.60%	12.40%
Georgia
Concentration Risk [Line Items]
Concentration risk percentage	10.50%	11.30%	10.70%	11.20%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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