Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017		Mar. 31, 2016	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 14,024			$ 27,468
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	14,049			27,534
Impaired Financing Receivable, with Related Allowance, Recorded Investment	102,617	[1]		79,931	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	102,914			80,205
Impaired Financing Receivable, Recorded Investment	116,641			107,399
Impaired Financing Receivable, Unpaid Principal Balance	116,963			107,739
Impaired Financing Receivable, Related Allowance	2,716			2,292
Financing Receivable, Recorded Investment, Nonaccrual Status	50,513	[3]		32,142	[4]
Impaired Financing Receivable, Average Recorded Investment	112,021		$ 77,007
Impaired Financing Receivable, Interest Income, Cash Basis Method	734		133
Crops [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,603			20,761
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	7,619			20,816
Impaired Financing Receivable, with Related Allowance, Recorded Investment	55,927	[1]		32,326	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	56,027			32,381
Impaired Financing Receivable, Recorded Investment	63,530			53,087
Impaired Financing Receivable, Unpaid Principal Balance	63,646			53,197
Impaired Financing Receivable, Related Allowance	1,240			945
Financing Receivable, Recorded Investment, Nonaccrual Status	17,801	[3]		13,405	[4]
Impaired Financing Receivable, Average Recorded Investment	58,309		23,555
Impaired Financing Receivable, Interest Income, Cash Basis Method	302		2
Permanent Plantings [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,665			3,683
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,669			3,688
Impaired Financing Receivable, with Related Allowance, Recorded Investment	29,515	[1]		26,748	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	29,579			26,817
Impaired Financing Receivable, Recorded Investment	33,180			30,431
Impaired Financing Receivable, Unpaid Principal Balance	33,248			30,505
Impaired Financing Receivable, Related Allowance	943			790
Financing Receivable, Recorded Investment, Nonaccrual Status	25,974	[3]		10,785	[4]
Impaired Financing Receivable, Average Recorded Investment	31,806		23,648
Impaired Financing Receivable, Interest Income, Cash Basis Method	152		44
Livestock [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	791			1,054
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	791			1,055
Impaired Financing Receivable, with Related Allowance, Recorded Investment	11,149	[1]		14,322	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	11,271			14,457
Impaired Financing Receivable, Recorded Investment	11,940			15,376
Impaired Financing Receivable, Unpaid Principal Balance	12,062			15,512
Impaired Financing Receivable, Related Allowance	397			399
Financing Receivable, Recorded Investment, Nonaccrual Status	1,941	[3]		2,696	[4]
Impaired Financing Receivable, Average Recorded Investment	13,658		16,318
Impaired Financing Receivable, Interest Income, Cash Basis Method	177		15
Part-Time Farm [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,965			1,970
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,970			1,975
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,026	[1]		6,535	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,037			6,550
Impaired Financing Receivable, Recorded Investment	7,991			8,505
Impaired Financing Receivable, Unpaid Principal Balance	8,007			8,525
Impaired Financing Receivable, Related Allowance	136			158
Financing Receivable, Recorded Investment, Nonaccrual Status	4,797	[3]		5,256	[4]
Impaired Financing Receivable, Average Recorded Investment	8,248		8,567
Impaired Financing Receivable, Interest Income, Cash Basis Method	103		72
Agriculture Storage and Processing [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0
Impaired Financing Receivable, Recorded Investment	0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0
Impaired Financing Receivable, Related Allowance	0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		4,919
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0
Other Commodity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0
Impaired Financing Receivable, Recorded Investment	0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0
Impaired Financing Receivable, Related Allowance	0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		$ 0
Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	101,000			76,500
Impaired Financing Receivable, Related Allowance	$ 2,300			$ 1,600
Impaired Financing Receivable, Impairment analysis performed percent	87.00%			71.00%
Less than 90 days past due [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 1,000	[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 $101.0 million (87 percent) of impaired loans as of March 31, 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 $1.0 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.