Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 24,857			$ 24,857			$ 24,951
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	24,472			24,472			24,733
Impaired Financing Receivable, with Related Allowance, Recorded Investment	64,326	[1]		64,326	[1]		72,116	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	63,491			63,491			70,308
Impaired Financing Receivable, Related Allowance	(2,573)			(2,573)			(2,696)
Impaired Financing Receivable, Recorded Investment	89,183			89,183			97,067
Impaired Financing Receivable, Unpaid Principal Balance	87,963			87,963			95,041
Financing Receivable, Recorded Investment, Nonaccrual Status	35,655	[3]		35,655	[3]		37,228	[4]
Impaired Financing Receivable, Average Recorded Investment	91,212		111,334	93,164		107,673
Impaired Financing Receivable, Interest Income, Accrual Method	319		300	881		1,364
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	8,284			8,284			6,956
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,071			8,071			6,825
Impaired Financing Receivable, with Related Allowance, Recorded Investment	13,763	[1]		13,763	[1]		16,697	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,157			13,157			16,284
Impaired Financing Receivable, Related Allowance	(356)			(356)			(406)
Impaired Financing Receivable, Recorded Investment	22,047			22,047			23,653
Impaired Financing Receivable, Unpaid Principal Balance	21,228			21,228			23,109
Financing Receivable, Recorded Investment, Nonaccrual Status	9,737	[3]		9,737	[3]		10,812	[4]
Impaired Financing Receivable, Average Recorded Investment	22,969		34,879	23,197		31,422
Impaired Financing Receivable, Interest Income, Accrual Method	105		61	275		403
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	8,411			8,411			9,880
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,364			8,364			9,877
Impaired Financing Receivable, with Related Allowance, Recorded Investment	34,256	[1]		34,256	[1]		36,146	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	33,749			33,749			34,978
Impaired Financing Receivable, Related Allowance	(1,686)			(1,686)			(1,702)
Impaired Financing Receivable, Recorded Investment	42,667			42,667			46,026
Impaired Financing Receivable, Unpaid Principal Balance	42,113			42,113			44,855
Financing Receivable, Recorded Investment, Nonaccrual Status	15,020	[3]		15,020	[3]		15,237	[4]
Impaired Financing Receivable, Average Recorded Investment	43,329		46,300	44,228		43,606
Impaired Financing Receivable, Interest Income, Accrual Method	76		123	270		497
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	6,417			6,417			6,671
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	6,284			6,284			6,588
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,898	[1]		5,898	[1]		7,600	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,119			6,119			7,455
Impaired Financing Receivable, Related Allowance	(167)			(167)			(193)
Impaired Financing Receivable, Recorded Investment	12,315			12,315			14,271
Impaired Financing Receivable, Unpaid Principal Balance	12,403			12,403			14,043
Financing Receivable, Recorded Investment, Nonaccrual Status	5,141	[3]		5,141	[3]		5,344	[4]
Impaired Financing Receivable, Average Recorded Investment	12,798		17,403	13,289		17,270
Impaired Financing Receivable, Interest Income, Accrual Method	59		38	135		192
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,745			1,745			1,444
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,753			1,753			1,443
Impaired Financing Receivable, with Related Allowance, Recorded Investment	10,409	[1]		10,409	[1]		11,554	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	10,466			10,466			11,476
Impaired Financing Receivable, Related Allowance	(364)			(364)			(392)
Impaired Financing Receivable, Recorded Investment	12,154			12,154			12,998
Impaired Financing Receivable, Unpaid Principal Balance	12,219			12,219			12,919
Financing Receivable, Recorded Investment, Nonaccrual Status	5,757	[3]		5,757	[3]		5,835	[4]
Impaired Financing Receivable, Average Recorded Investment	12,116		12,181	12,410		13,207
Impaired Financing Receivable, Interest Income, Accrual Method	79		78	201		272
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [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, Related Allowance	0			0			0
Impaired Financing Receivable, Recorded Investment	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		0	0		1,446
Impaired Financing Receivable, Interest Income, Accrual Method	0		0	0		0
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [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]		119	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			115
Impaired Financing Receivable, Related Allowance	0			0			(3)
Impaired Financing Receivable, Recorded Investment	0			0			119
Impaired Financing Receivable, Unpaid Principal Balance	0			0			115
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		571	40		722
Impaired Financing Receivable, Interest Income, Accrual Method	0		0	0		0
Less than 90 days past due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	10,500	[3]		10,500	[3]		9,600	[4]
Collateral Dependent Not Individually Analyzed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Related Allowance	(1,300)			(1,300)			(1,300)
Impaired Financing Receivable, Recorded Investment	$ 57,100			$ 57,100			$ 65,100
Impaired Financing Receivable, Impairment analysis performed percent	64.00%	[1]		64.00%	[1]		67.00%

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $57.1 million (64 percent) of impaired loans as of June 30, 2014, which resulted in a specific reserve of $1.3 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $65.1 million (67 percent) of impaired loans as of December 31, 2013, which resulted in a specific reserve of $1.3 million.

[3] Includes $10.5 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 $9.6 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.