Subsequent Events (Details) $ / shares in Units, $ in Thousands										3 Months Ended	9 Months Ended
	Nov. 08, 2017 $ / shares	Oct. 31, 2017 USD ($) item shares	Oct. 23, 2017 USD ($)	Aug. 17, 2017	Aug. 10, 2017 USD ($)	Jul. 19, 2017 shares	Jul. 10, 2017 shares	Apr. 12, 2017 shares	Mar. 27, 2017 shares	Dec. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($) item	Dec. 31, 2016 USD ($)
Subsequent Events
Total consideration											$ 7,446
Repayment of principal											20,819	$ 84,750
Debt outstanding											465,834		$ 309,862
Debt maturing prior to the end of 2017											$ 60,400
Number of acquisitions | item											15	16
Payments to acquire farmland											$ 92,680	$ 122,388
Farmer Mac Bond #2
Subsequent Events
Repayment of principal			$ 5,500
Debt outstanding											$ 5,460		$ 5,460
Subsequent event
Subsequent Events
Shares repurchased (in shares) | shares										279,210
Shares repurchased, average price (in dollars per share) | $ / shares										$ 9.15
Total consideration										$ 2,600
Dividend declared (per share) | $ / shares	$ 0.1275
Subsequent event | Farmer Mac Bond #2
Subsequent Events
Repayment of principal			5,500
Subsequent event | South Carolina
Subsequent Events
Number of acquisitions | item		1
Payments to acquire farmland		$ 2,200
Farmer Mac Facility | Subsequent event
Subsequent Events
Debt outstanding			129,300
Debt maturing prior to the end of 2017			$ 54,900
Series B Participating Preferred Stock
Subsequent Events
Repayment of principal					$ 1,100
Preference dividend (as a percent)				6.00%
Series B Participating Preferred Stock | Subsequent event
Subsequent Events
Dividend declared (per share) | $ / shares	$ 0.375
Preference dividend (as a percent)	6.00%
Common stock
Subsequent Events
Shares repurchased (in shares) | shares						531,827	118,634	328,122	129,174
Common stock issued (in shares) | shares						531,827	118,634	328,122	129,174
Common stock | Subsequent event
Subsequent Events
Common stock issued (in shares) | shares		984,365
Common units | Subsequent event
Subsequent Events
Shares repurchased (in shares) | shares		984,365