Loans and Allowance for Losses and Concentrations of Credit Risk - Allowance for Credit Losses Roll Forward (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	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Loan Losses	$ 5,770		$ 5,770			$ 6,866
Reserve for losses	5,595		5,595			6,468
Total Allowance for Losses	11,365	13,478	11,365	13,478	13,979	13,334	14,252	16,890
Provision for loan losses	1,583	529	1,010	99
(Release of)/provision for reserve for losses	(974)	(175)	(873)	571
Total provision for losses	(2,557)	(704)	(1,883)	472
Total Allowance for Losses - Charge-offs	(57)	(70)	(86)	(3,884)
Eligible Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Loan Losses	5,770	7,368	5,770	7,368	7,410	6,866	7,967	11,351
Provision for loan losses	1,583	529	1,010	99
Allowance for Loan Losses - Charge-offs	(57)	(70)	(86)	(3,884)
Long-Term Standby Purchase Commitments and Farmer Mac Guaranteed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve for losses	5,595	6,110	5,595	6,110	6,569	6,468	6,285	5,539
(Release of)/provision for reserve for losses	(974)	(175)	(873)	571
Reserve for Losses - Charge-offs	0	0	0	0
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	4,999	7,196	4,999	7,196	7,715	7,292	6,971	9,661
Total provision for losses	(2,716)	225	(2,293)	1,160
Total Allowance for Losses - Charge-offs	0	0	0	(3,625)
Agriculture Storage and Processing [Member] | Eligible Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Loan Losses - Charge-offs				(3,600)
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	2,390	2,405	2,390	2,405	2,278	2,124	2,617	2,589
Total provision for losses	112	(212)	266	(184)
Total Allowance for Losses - Charge-offs	0	0	0	0
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	2,217	2,168	2,217	2,168	2,131	2,186	2,326	2,316
Total provision for losses	86	(158)	31	41
Total Allowance for Losses - Charge-offs	0	0	0	(189)
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	1,311	1,279	1,311	1,279	1,387	1,271	1,587	1,534
Total provision for losses	(19)	(308)	97	(255)
Total Allowance for Losses - Charge-offs	(57)	0	(57)	0
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	444	425	444	425	464	454	733	784
Total provision for losses	(20)	(238)	19	(289)
Total Allowance for Losses - Charge-offs	0	(70)	(29)	(70)
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Allowance for Losses	4	5	4	5	4	7	18	6
Total provision for losses	0	(13)	(3)	(1)
Total Allowance for Losses - Charge-offs	$ 0	$ 0	$ 0	$ 0