Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 15,831			$ 15,831			$ 27,468
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	15,837			15,837			27,534
Impaired Financing Receivable, with Related Allowance, Recorded Investment	105,607	[1]		105,607	[1]		79,931	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	105,653			105,653			80,205
Impaired Financing Receivable, Recorded Investment	121,438			121,438			107,399
Impaired Financing Receivable, Unpaid Principal Balance	121,490			121,490			107,739
Impaired Financing Receivable, Related Allowance	2,592			2,592			2,292
Financing Receivable, Recorded Investment, Nonaccrual Status	52,781	[3]		52,781	[3]		32,142	[4]
Impaired Financing Receivable, Average Recorded Investment	119,040		$ 76,520	115,161		$ 86,179
Impaired Financing Receivable, Interest Income, Cash Basis Method	321		807	1,055		940
Crops [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	9,011			9,011			20,761
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,016			9,016			20,816
Impaired Financing Receivable, with Related Allowance, Recorded Investment	58,049	[1]		58,049	[1]		32,326	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	58,073			58,073			32,381
Impaired Financing Receivable, Recorded Investment	67,060			67,060			53,087
Impaired Financing Receivable, Unpaid Principal Balance	67,089			67,089			53,197
Impaired Financing Receivable, Related Allowance	1,241			1,241			945
Financing Receivable, Recorded Investment, Nonaccrual Status	20,270	[3]		20,270	[3]		13,405	[4]
Impaired Financing Receivable, Average Recorded Investment	65,295		28,732	61,226		26,121
Impaired Financing Receivable, Interest Income, Cash Basis Method	160		60	462		62
Permanent Plantings [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,657			3,657			3,683
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,657			3,657			3,688
Impaired Financing Receivable, with Related Allowance, Recorded Investment	29,607	[1]		29,607	[1]		26,748	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	29,622			29,622			26,817
Impaired Financing Receivable, Recorded Investment	33,264			33,264			30,431
Impaired Financing Receivable, Unpaid Principal Balance	33,279			33,279			30,505
Impaired Financing Receivable, Related Allowance	940			940			790
Financing Receivable, Recorded Investment, Nonaccrual Status	25,838	[3]		25,838	[3]		10,785	[4]
Impaired Financing Receivable, Average Recorded Investment	33,222		24,133	32,292		29,673
Impaired Financing Receivable, Interest Income, Cash Basis Method	68		509	220		553
Livestock [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,204			1,204			1,054
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,204			1,204			1,055
Impaired Financing Receivable, with Related Allowance, Recorded Investment	11,970	[1]		11,970	[1]		14,322	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	11,974			11,974			14,457
Impaired Financing Receivable, Recorded Investment	13,174			13,174			15,376
Impaired Financing Receivable, Unpaid Principal Balance	13,178			13,178			15,512
Impaired Financing Receivable, Related Allowance	256			256			399
Financing Receivable, Recorded Investment, Nonaccrual Status	1,902	[3]		1,902	[3]		2,696	[4]
Impaired Financing Receivable, Average Recorded Investment	12,557		14,883	13,497		13,906
Impaired Financing Receivable, Interest Income, Cash Basis Method	22		133	199		148
Part-Time Farm [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,959			1,959			1,970
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,960			1,960			1,975
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,901	[1]		5,901	[1]		6,535	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,904			5,904			6,550
Impaired Financing Receivable, Recorded Investment	7,860			7,860			8,505
Impaired Financing Receivable, Unpaid Principal Balance	7,864			7,864			8,525
Impaired Financing Receivable, Related Allowance	153			153			158
Financing Receivable, Recorded Investment, Nonaccrual Status	4,771	[3]		4,771	[3]		5,256	[4]
Impaired Financing Receivable, Average Recorded Investment	7,926		8,772	8,119		9,111
Impaired Financing Receivable, Interest Income, Cash Basis Method	71		105	174		177
Agriculture Storage and Processing [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		0	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Recorded Investment	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Related Allowance	0			0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		0	0		7,368
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0	0		0
Other Commodity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	80	[1]		80	[1]		0	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	80			80			0
Impaired Financing Receivable, Recorded Investment	80			80			0
Impaired Financing Receivable, Unpaid Principal Balance	80			80			0
Impaired Financing Receivable, Related Allowance	2			2			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	40		0	27		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		$ 0	0		$ 0
Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	104,200			104,200			76,500
Impaired Financing Receivable, Related Allowance	$ 2,300			$ 2,300			$ 1,600
Impaired Financing Receivable, Impairment analysis performed percent	86.00%			86.00%			71.00%
Less than 90 days past due [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 11,300	[3]		$ 11,300	[3]		$ 12,400	[4]

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $104.2 million (86 percent) of impaired loans as of June 30, 2017, which resulted in a specific allowance of $2.3 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $76.5 million (71 percent) of impaired loans as of December 31, 2016, which resulted in a specific allowance of $1.6 million.

[3] Includes $11.3 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.

[4] Includes $12.4 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.