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, 2015		Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Payments to Acquire Other Loans and Leases Held-for-investment	$ 1,300			$ 1,981		$ 440
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	16,195			16,195			$ 22,291
Impaired Financing Receivable, with Related Allowance, Recorded Investment	89,588	[1]		89,588	[1]		61,772	[2]
Impaired Financing Receivable, Recorded Investment	105,783			105,783			84,063
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	16,156			16,156			21,840
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	89,290			89,290			60,597
Impaired Financing Receivable, Unpaid Principal Balance	105,446			105,446			82,437
Impaired Financing Receivable, Related Allowance	5,510			5,510			2,637
Financing Receivable, Recorded Investment, Nonaccrual Status	38,617	[3]		38,617	[3]		30,152	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	98,660		$ 91,212	93,794		93,164
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	341		319	912		881
Financing Receivable, Modifications, Pre-Modification Recorded Investment	1,100		300	1,100
Crops [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,272			4,272			4,877
Impaired Financing Receivable, with Related Allowance, Recorded Investment	21,706	[1]		21,706	[1]		10,753	[2]
Impaired Financing Receivable, Recorded Investment	25,978			25,978			15,630
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,231			4,231			4,723
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	21,706			21,706			10,042
Impaired Financing Receivable, Unpaid Principal Balance	25,937			25,937			14,765
Impaired Financing Receivable, Related Allowance	536			536			397
Financing Receivable, Recorded Investment, Nonaccrual Status	3,608	[3]		3,608	[3]		5,168	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	24,392		22,969	21,471		23,197
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	58		105	340		275
Permanent Plantings [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	6,352			6,352			5,837
Impaired Financing Receivable, with Related Allowance, Recorded Investment	36,342	[1]		36,342	[1]		33,690	[2]
Impaired Financing Receivable, Recorded Investment	42,694			42,694			39,527
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	6,354			6,354			5,750
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	36,054			36,054			33,393
Impaired Financing Receivable, Unpaid Principal Balance	42,408			42,408			39,143
Impaired Financing Receivable, Related Allowance	1,623			1,623			1,515
Financing Receivable, Recorded Investment, Nonaccrual Status	24,835	[3]		24,835	[3]		14,413	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	42,347		43,329	41,407		44,228
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	142		76	225		270
Livestock [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,085			4,085			9,576
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,341	[1]		9,341	[1]		5,979	[2]
Impaired Financing Receivable, Recorded Investment	13,426			13,426			15,555
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,085			4,085			9,386
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	9,335			9,335			5,897
Impaired Financing Receivable, Unpaid Principal Balance	13,420			13,420			15,283
Impaired Financing Receivable, Related Allowance	799			799			361
Financing Receivable, Recorded Investment, Nonaccrual Status	4,230	[3]		4,230	[3]		4,438	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	14,247		12,798	14,683		13,289
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	49		59	197		135
Part-Time Farm [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,486			1,486			2,001
Impaired Financing Receivable, with Related Allowance, Recorded Investment	8,699	[1]		8,699	[1]		11,350	[2]
Impaired Financing Receivable, Recorded Investment	10,185			10,185			13,351
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,486			1,486			1,981
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	8,695			8,695			11,265
Impaired Financing Receivable, Unpaid Principal Balance	10,181			10,181			13,246
Impaired Financing Receivable, Related Allowance	298			298			364
Financing Receivable, Recorded Investment, Nonaccrual Status	5,944	[3]		5,944	[3]		6,133	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	10,924		12,116	11,733		12,410
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	92		79	150		201
Agriculture Storage and Processing [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	13,500	[1]		13,500	[1]		0	[2]
Impaired Financing Receivable, Recorded Investment	13,500			13,500			0
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,500			13,500			0
Impaired Financing Receivable, Unpaid Principal Balance	13,500			13,500			0
Impaired Financing Receivable, Related Allowance	2,254			2,254			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	6,750		0	4,500		0
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0	0		0
Other Commodity [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		0	[2]
Impaired Financing Receivable, Recorded Investment	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	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 [Abstract]
Impaired Financing Receivable, Average Recorded Investment	0		0	0		40
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		$ 0	0		$ 0
Collateral Dependent Not Individually Analyzed [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, Recorded Investment	77,700			77,700			54,400
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, Related Allowance	$ 3,800			$ 3,800			$ (1,200)
Impaired Financing Receivable, Impairment analysis performed percent	73.00%			73.00%			65.00%
Less than 90 days past due [Member]
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 12,500	[3]		$ 12,500	[3]		$ 11,700	[4]

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $77.7 million (73 percent) of impaired loans as of June 30, 2015, which resulted in a specific reserve of $3.8 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $54.4 million (65 percent) of impaired loans as of December 31, 2014, which resulted in a specific reserve of $1.2 million.

[3] Includes $12.5 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 $11.7 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.