Concentration Risk (Details) - Geographic concentration	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Approximate total acres
Concentration Risk
Concentration risk (as a percent)	100.00%	100.00%
Approximate total acres | Corn Belt
Concentration Risk
Concentration risk (as a percent)	31.60%	30.90%
Approximate total acres | Delta + South
Concentration Risk
Concentration risk (as a percent)	18.30%	22.60%
Approximate total acres | High Plains
Concentration Risk
Concentration risk (as a percent)	19.30%	23.70%
Approximate total acres | Southeast
Concentration Risk
Concentration risk (as a percent)	26.50%	22.80%
Approximate total acres | West Coast
Concentration Risk
Concentration risk (as a percent)	4.30%
Rental income
Concentration Risk
Concentration risk (as a percent)	100.00%	100.00%
Rental income | Corn Belt
Concentration Risk
Concentration risk (as a percent)	46.30%	28.60%
Rental income | Delta + South
Concentration Risk
Concentration risk (as a percent)	9.70%	11.70%
Rental income | High Plains
Concentration Risk
Concentration risk (as a percent)	9.90%	17.40%
Rental income | Southeast
Concentration Risk
Concentration risk (as a percent)	17.20%	42.30%
Rental income | West Coast
Concentration Risk
Concentration risk (as a percent)	16.90%