Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Net credit losses (recoveries)	$ 154		$ 3,853		$ (6)
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	27,468		23,607
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	27,534		23,562
Impaired Financing Receivable, with Related Allowance, Recorded Investment	79,931	[1]	52,115	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	80,205		52,133
Impaired Financing Receivable, Recorded Investment	107,399		75,722
Impaired Financing Receivable, Unpaid Principal Balance	107,739		75,695
Impaired Financing Receivable, Related Allowance	2,292		1,850
Financing Receivable, Recorded Investment, Nonaccrual Status	32,142	[3]	41,672	[4]
Impaired Financing Receivable, Average Recorded Investment	82,803		90,691
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,569		1,514
Crops [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	20,761		3,772
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	20,816		3,720
Impaired Financing Receivable, with Related Allowance, Recorded Investment	32,326	[1]	15,103	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	32,381		15,020
Impaired Financing Receivable, Recorded Investment	53,087		18,875
Impaired Financing Receivable, Unpaid Principal Balance	53,197		18,740
Impaired Financing Receivable, Related Allowance	945		476
Financing Receivable, Recorded Investment, Nonaccrual Status	13,405	[3]	5,105	[4]
Impaired Financing Receivable, Average Recorded Investment	33,252		22,315
Impaired Financing Receivable, Interest Income, Cash Basis Method	136		381
Permanent Plantings [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,683		12,340
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,688		12,346
Impaired Financing Receivable, with Related Allowance, Recorded Investment	26,748	[1]	11,939	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	26,817		11,938
Impaired Financing Receivable, Recorded Investment	30,431		24,279
Impaired Financing Receivable, Unpaid Principal Balance	30,505		24,284
Impaired Financing Receivable, Related Allowance	790		360
Financing Receivable, Recorded Investment, Nonaccrual Status	10,785	[3]	16,546	[4]
Impaired Financing Receivable, Average Recorded Investment	24,737		36,326
Impaired Financing Receivable, Interest Income, Cash Basis Method	866		472
Livestock [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,054		5,644
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,055		5,645
Impaired Financing Receivable, with Related Allowance, Recorded Investment	14,322	[1]	9,050	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	14,457		9,153
Impaired Financing Receivable, Recorded Investment	15,376		14,694
Impaired Financing Receivable, Unpaid Principal Balance	15,512		14,798
Impaired Financing Receivable, Related Allowance	399		787
Financing Receivable, Recorded Investment, Nonaccrual Status	2,696	[3]	4,313	[4]
Impaired Financing Receivable, Average Recorded Investment	14,450		14,077
Impaired Financing Receivable, Interest Income, Cash Basis Method	238		353
Part-Time Farm [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,970		1,851
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,975		1,851
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,535	[1]	6,185	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,550		6,184
Impaired Financing Receivable, Recorded Investment	8,505		8,036
Impaired Financing Receivable, Unpaid Principal Balance	8,525		8,035
Impaired Financing Receivable, Related Allowance	158		227
Financing Receivable, Recorded Investment, Nonaccrual Status	5,256	[3]	5,870	[4]
Impaired Financing Receivable, Average Recorded Investment	8,396		10,605
Impaired Financing Receivable, Interest Income, Cash Basis Method	329		308
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]	9,838	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		9,838
Impaired Financing Receivable, Recorded Investment	0		9,838
Impaired Financing Receivable, Unpaid Principal Balance	0		9,838
Impaired Financing Receivable, Related Allowance	0		0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]	9,838	[4]
Impaired Financing Receivable, Average Recorded Investment	1,968		7,368
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	76,500		46,400
Impaired Financing Receivable, Related Allowance	$ 1,600		$ 1,000
Impaired Financing Receivable, Impairment analysis performed percent	71.00%		61.00%
Less than 90 days past due [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 12,400	[3]	$ 14,700	[4]
Off-balance sheet [Member]
Financing Receivable, Impaired [Line Items]
Net credit losses (recoveries)	0		0		0
On-balance sheet [Member]
Financing Receivable, Impaired [Line Items]
Net credit losses (recoveries)	$ 154		$ 3,853		$ (6)

[1] 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.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $46.4 million (61 percent) of impaired loans as of December 31, 2015, which resulted in a specific allowance of $1.0 million.

[3] 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.

[4] Includes $14.7 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.