Loans and Allowance for Losses and Concentrations of Credit Risk - Allowance for Losses by Impairment Method and Commodity (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	$ 5,201,898		$ 5,068,039
Financing Receivable, Individually Evaluated for Impairment	92,077		95,041
Financing Receivable, Gross	5,293,975	[1]	5,163,080	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	11,287		10,638
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,692		2,696
Total Allowance for Losses	13,979		13,334		14,252	16,890
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	2,738,425		2,643,748
Financing Receivable, Individually Evaluated for Impairment	23,170		23,109
Financing Receivable, Gross	2,761,595	[1]	2,666,857	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,832		1,718
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	446		406
Total Allowance for Losses	2,278		2,124		2,617	2,589
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	864,807		862,969
Financing Receivable, Individually Evaluated for Impairment	43,239		44,855
Financing Receivable, Gross	908,046	[1]	907,824	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	456		484
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,675		1,702
Total Allowance for Losses	2,131		2,186		2,326	2,316
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	1,268,365		1,232,062
Financing Receivable, Individually Evaluated for Impairment	13,462		14,043
Financing Receivable, Gross	1,281,827	[1]	1,246,105	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,208		1,078
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	179		193
Total Allowance for Losses	1,387		1,271		1,587	1,534
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	145,588		149,824
Financing Receivable, Individually Evaluated for Impairment	12,206		12,919
Financing Receivable, Gross	157,794	[1]	162,743	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	72		62
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	392		392
Total Allowance for Losses	464		454		733	784
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	175,525		170,918
Financing Receivable, Individually Evaluated for Impairment	0		0
Financing Receivable, Gross	175,525	[1]	170,918	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	7,715		7,292
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Total Allowance for Losses	7,715		7,292		6,971	9,661
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	9,188		8,518
Financing Receivable, Individually Evaluated for Impairment	0		115
Financing Receivable, Gross	9,188	[1]	8,633	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4		4
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		3
Total Allowance for Losses	4		7		18	6
On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	2,143,123		2,051,498
Financing Receivable, Individually Evaluated for Impairment	79,835		83,969
Financing Receivable, Gross	2,222,958	[1]	2,135,467	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4,982		4,392
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,428		2,474
Total Allowance for Losses	7,410		6,866
On-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	1,395,277		1,363,861
Financing Receivable, Individually Evaluated for Impairment	19,854		21,147
Financing Receivable, Gross	1,415,131	[1]	1,385,008	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,469		1,321
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	361		362
Total Allowance for Losses	1,830		1,683
On-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	306,566		295,037
Financing Receivable, Individually Evaluated for Impairment	39,864		41,441
Financing Receivable, Gross	346,430	[1]	336,478	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	301		325
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,608		1,641
Total Allowance for Losses	1,909		1,966
On-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	359,633		319,665
Financing Receivable, Individually Evaluated for Impairment	9,193		10,844
Financing Receivable, Gross	368,826	[1]	330,509	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	582		436
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	100		140
Total Allowance for Losses	682		576
On-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	38,605		39,940
Financing Receivable, Individually Evaluated for Impairment	10,924		10,422
Financing Receivable, Gross	49,529	[1]	50,362	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	24		20
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	359		331
Total Allowance for Losses	383		351
On-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	41,717		32,636
Financing Receivable, Individually Evaluated for Impairment	0		0
Financing Receivable, Gross	41,717	[1]	32,636	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,606		2,290
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Total Allowance for Losses	2,606		2,290
On-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	1,325		359
Financing Receivable, Individually Evaluated for Impairment	0		115
Financing Receivable, Gross	1,325	[1]	474	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Total Allowance for Losses	0		0
Off-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	3,058,775		3,016,541
Financing Receivable, Individually Evaluated for Impairment	12,242		11,072
Financing Receivable, Gross	3,071,017	[1]	3,027,613	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	6,305		6,246
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	264		222
Total Allowance for Losses	6,569		6,468
Off-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	1,343,148		1,279,887
Financing Receivable, Individually Evaluated for Impairment	3,316		1,962
Financing Receivable, Gross	1,346,464	[1]	1,281,849	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	363		397
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	85		44
Total Allowance for Losses	448		441
Off-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	558,241		567,932
Financing Receivable, Individually Evaluated for Impairment	3,375		3,414
Financing Receivable, Gross	561,616	[1]	571,346	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	155		159
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	67		61
Total Allowance for Losses	222		220
Off-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	908,732		912,397
Financing Receivable, Individually Evaluated for Impairment	4,269		3,199
Financing Receivable, Gross	913,001	[1]	915,596	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	626		642
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	79		53
Total Allowance for Losses	705		695
Off-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	106,983		109,884
Financing Receivable, Individually Evaluated for Impairment	1,282		2,497
Financing Receivable, Gross	108,265	[1]	112,381	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	48		42
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	33		61
Total Allowance for Losses	81		103
Off-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	133,808		138,282
Financing Receivable, Individually Evaluated for Impairment	0		0
Financing Receivable, Gross	133,808	[1]	138,282	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	5,109		5,002
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Total Allowance for Losses	5,109		5,002
Off-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Collectively Evaluated for Impairment	7,863		8,159
Financing Receivable, Individually Evaluated for Impairment	0		0
Financing Receivable, Gross	7,863	[1]	8,159	[1]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4		4
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		3
Total Allowance for Losses	$ 4		$ 7

[1] Amounts represent unpaid principal balance of risk-rated loans, which is the basis Farmer Mac uses to analyze its portfolio, and recorded investment of past due loans.