Concentration Risk (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) tenant	Mar. 31, 2019 USD ($)
Concentration Risk
Number of significant tenants | tenant	1
Rental income recognized	$ 10,073	$ 9,672
Approximate total acres | Geographic concentration
Concentration Risk
Concentration risk (as a percent)	100.00%	100.00%
Approximate total acres | Geographic concentration | Cornbelt
Concentration Risk
Concentration risk (as a percent)	27.70%	28.00%
Approximate total acres | Geographic concentration | Delta and South
Concentration Risk
Concentration risk (as a percent)	17.60%	17.30%
Approximate total acres | Geographic concentration | High Plains
Concentration Risk
Concentration risk (as a percent)	20.00%	19.20%
Approximate total acres | Geographic concentration | Southeast
Concentration Risk
Concentration risk (as a percent)	27.40%	28.40%
Approximate total acres | Geographic concentration | West Coast
Concentration Risk
Concentration risk (as a percent)	7.30%	7.10%
Rental income | Tenant concentration | Tenant C
Concentration Risk
Rental income recognized	$ 1,198	$ 163
Concentration risk (as a percent)	11.60%	1.70%
Rental income | Geographic concentration
Concentration Risk
Concentration risk (as a percent)	100.00%	100.00%
Rental income | Geographic concentration | Cornbelt
Concentration Risk
Concentration risk (as a percent)	32.10%	36.10%
Rental income | Geographic concentration | Delta and South
Concentration Risk
Concentration risk (as a percent)	10.20%	11.50%
Rental income | Geographic concentration | High Plains
Concentration Risk
Concentration risk (as a percent)	7.80%	6.60%
Rental income | Geographic concentration | Southeast
Concentration Risk
Concentration risk (as a percent)	23.50%	25.70%
Rental income | Geographic concentration | West Coast
Concentration Risk
Concentration risk (as a percent)	26.40%	20.10%