Real Estate and Intangible Assets - 2016 Acquisitions (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) a farm	Dec. 31, 2016 USD ($) a farm option transaction shares	Dec. 31, 2015 USD ($)	Nov. 30, 2017 a
Real Estate Properties [Line Items]
Number of farms | farm	73	58
Total Acres | a	63,014	50,592
New Long-term Debt Issued	$ 302,988,000
Payments of stock issuance costs	1,977,000	$ 272,000	$ 1,482,000
Rental revenue	$ 25,111,000	$ 17,306,000	$ 11,888,000
Hillsborough, FL
Real Estate Properties [Line Items]
Total Acres | a				219
2016 New Real Estate Activity
Real Estate Properties [Line Items]
Number of farms | farm		15
Number of separate transactions | transaction		9
Total Acres | a		33,780
Total Purchase Price		$ 99,722,000
Acquisition Costs		496,000
New Long-term Debt Issued		32,853,000
Acquisition costs, period cost		206,000
Rental revenue		2,600,000
Real estate properties earnings recognized		196,000
2016 New Real Estate Activity | Leasehold interests – land
Real Estate Properties [Line Items]
Acquisition costs, period cost		$ 9,520
2016 New Real Estate Activity | Gunbarrel Road | Saguache, CO
Real Estate Properties [Line Items]
Number of farms | farm		3
Acquisition Date		Mar. 03, 2016
Total Acres | a		6,191
Lessee term		5 years
Total Purchase Price		$ 25,736,000
Acquisition Costs		119,000
Annualized straight-line rent		1,591,000
New Long-term Debt Issued		$ 15,531,000
Number of renewal options | option		1
Term of renewal		5 years
Business acquisition, equity interest issued or issuable (in shares) | shares		745,879
Business acquisition, equity interest issued or issuable, value assigned		$ 6,500,000
Payments of stock issuance costs		$ 25,500
2016 New Real Estate Activity | Calaveras Avenue | Fresno, CA
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Apr. 05, 2016
Total Acres | a		453
Lessee term		10 years
Total Purchase Price		$ 15,470,000
Acquisition Costs		38,000
Annualized straight-line rent		774,000
New Long-term Debt Issued		$ 9,282,000
Number of renewal options | option		1
Term of renewal		5 years
2016 New Real Estate Activity | Orange Avenue | St. Lucie, FL
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Jul. 01, 2016
Total Acres | a		401
Lessee term		7 years
Total Purchase Price		$ 5,100,000
Acquisition Costs		38,000
Annualized straight-line rent		291,000
New Long-term Debt Issued		$ 3,120,000
Number of renewal options | option		2
Term of renewal		7 years
2016 New Real Estate Activity | Lithia Road | Hillsborough, FL
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Aug. 11, 2016
Total Acres | a		72
Lessee term		5 years
Total Purchase Price		$ 1,700,000
Acquisition Costs		38,000
Annualized straight-line rent		97,000
New Long-term Debt Issued		$ 1,020,000
Number of renewal options | option		0
2016 New Real Estate Activity | Baca County | Baca, CO
Real Estate Properties [Line Items]
Number of farms | farm		5
Acquisition Date		Sep. 01, 2016
Total Acres | a		7,384
Lessee term		4 years
Total Purchase Price		$ 6,323,000
Acquisition Costs		73,000
Annualized straight-line rent		384,000
New Long-term Debt Issued		$ 0
Number of renewal options | option		1
Term of renewal		5 years
Business acquisition, equity interest issued or issuable (in shares) | shares		125,677
Business acquisition, equity interest issued or issuable, value assigned		$ 1,500,000
Payments of stock issuance costs		$ 8,235
2016 New Real Estate Activity | Diego Ranch | Stanislaus, CA
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Sep. 14, 2016
Total Acres | a		1,357
Lessee term		3 years
Total Purchase Price		$ 13,996,000
Acquisition Costs		64,000
Annualized straight-line rent		621,000
New Long-term Debt Issued		$ 0
Business acquisition, equity interest issued or issuable (in shares) | shares		343,750
Business acquisition, equity interest issued or issuable, value assigned		$ 3,900,000
Payments of stock issuance costs		$ 21,710
2016 New Real Estate Activity | Nevada Ranch | Merced, CA
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Sep. 14, 2016
Total Acres | a		1,130
Lessee term		3 years
Total Purchase Price		$ 13,232,000
Acquisition Costs		42,000
Annualized straight-line rent		574,000
New Long-term Debt Issued		$ 0
2016 New Real Estate Activity | Central Avenue | Fresno, CA
Real Estate Properties [Line Items]
Number of farms | farm		1
Acquisition Date		Oct. 13, 2016
Total Acres | a		197
Lessee term		10 years
Total Purchase Price		$ 6,500,000
Acquisition Costs		29,000
Annualized straight-line rent		325,000
New Long-term Debt Issued		$ 3,900,000
Number of renewal options | option		2
Term of renewal		5 years
2016 New Real Estate Activity | Horse Creek | Baca, CO
Real Estate Properties [Line Items]
Number of farms | farm		1
Total Acres | a		16,595
Lessee term		4 years
Total Purchase Price		$ 11,665,000
Acquisition Costs		55,000
Annualized straight-line rent		717,000
New Long-term Debt Issued		$ 0
Number of renewal options | option		1
Term of renewal		5 years
Business acquisition, equity interest issued or issuable (in shares) | shares		233,952
Business acquisition, equity interest issued or issuable, value assigned		$ 2,600,000
Payments of stock issuance costs		$ 7,675
Lease One | 2016 New Real Estate Activity | Diego Ranch | Stanislaus, CA
Real Estate Properties [Line Items]
Number of renewal options | option		3
Term of renewal		5 years
Lease One | 2016 New Real Estate Activity | Nevada Ranch | Merced, CA
Real Estate Properties [Line Items]
Number of renewal options | option		1
Term of renewal		5 years
Lease Two | 2016 New Real Estate Activity | Diego Ranch | Stanislaus, CA
Real Estate Properties [Line Items]
Number of renewal options | option		1
Term of renewal		3 years
Lease Two | 2016 New Real Estate Activity | Nevada Ranch | Merced, CA
Real Estate Properties [Line Items]
Number of renewal options | option		1
Term of renewal		3 years