Loans and Allowance for Losses and Concentrations of Credit Risk Financing Receivables Credit Quality Indicators (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	$ 4,782,609	[1]	$ 4,747,289	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	39,663	[2]	33,263	[2]
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,235,600	[1]	2,171,349	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	8,103	[2]	4,668	[2]
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	869,129	[1]	882,532	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	17,003	[2]	10,801	[2]
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,256,349	[1]	1,287,741	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	9,781	[2]	7,222	[2]
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	189,584	[1]	201,865	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	4,657	[2]	6,118	[2]
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	220,938	[1]	191,786	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[2]	4,337	[2]
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	11,009	[1]	12,016	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	119	[2]	117	[2]
On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,704,544	[1]	1,679,851	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	32,198	[2]	29,592	[2]
On-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,030,732	[1]	999,566	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	3,828	[2]	3,971	[2]
On-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	292,877	[1]	289,694	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	16,961	[2]	10,756	[2]
On-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	278,260	[1]	280,380	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	6,905	[2]	4,389	[2]
On-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	59,110	[1]	62,947	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	4,385	[2]	6,022	[2]
On-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	43,450	[1]	47,149	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[2]	4,337	[2]
On-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	115	[1]	115	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	119	[2]	117	[2]
Off-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	3,078,065	[1]	3,067,438	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	7,465	[2]	3,671	[2]
Off-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,204,868	[1]	1,171,783	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	4,275	[2]	697	[2]
Off-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	576,252	[1]	592,838	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	42	[2]	45	[2]
Off-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	978,089	[1]	1,007,361	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,876	[2]	2,833	[2]
Off-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	130,474	[1]	138,918	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	272	[2]	96	[2]
Off-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	177,488	[1]	144,637	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[2]	0	[2]
Off-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	10,894	[1]	11,901	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[2]	0	[2]
Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	4,422,928	[1]	4,374,938	[1]
Pass [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,146,605	[1]	2,090,887	[1]
Pass [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	778,192	[1]	793,317	[1]
Pass [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,159,541	[1]	1,174,779	[1]
Pass [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	168,103	[1]	178,713	[1]
Pass [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	161,200	[1]	126,955	[1]
Pass [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	9,287	[1]	10,287	[1]
Pass [Member] | On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,507,776	[1]	1,486,003	[1]
Pass [Member] | On-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	970,854	[1]	947,097	[1]
Pass [Member] | On-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	226,463	[1]	226,253	[1]
Pass [Member] | On-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	251,822	[1]	252,525	[1]
Pass [Member] | On-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	45,379	[1]	48,156	[1]
Pass [Member] | On-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	13,258	[1]	11,972	[1]
Pass [Member] | On-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	0	[1]	0	[1]
Pass [Member] | Off-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,915,152	[1]	2,888,935	[1]
Pass [Member] | Off-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,175,751	[1]	1,143,790	[1]
Pass [Member] | Off-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	551,729	[1]	567,064	[1]
Pass [Member] | Off-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	907,719	[1]	922,254	[1]
Pass [Member] | Off-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	122,724	[1]	130,557	[1]
Pass [Member] | Off-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	147,942	[1]	114,983	[1]
Pass [Member] | Off-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	9,287	[1]	10,287	[1]
Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	136,322	[1],[3]	185,837	[1],[3]
Special Mention [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	36,827	[1],[3]	40,925	[1],[3]
Special Mention [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	26,975	[1],[3]	38,862	[1],[3]
Special Mention [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	48,303	[1],[3]	56,754	[1],[3]
Special Mention [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	6,217	[1],[3]	5,351	[1],[3]
Special Mention [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	17,402	[1],[3]	43,353	[1],[3]
Special Mention [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	598	[1],[3]	592	[1],[3]
Special Mention [Member] | On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	72,781	[1],[3]	102,716	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	28,572	[1],[3]	30,466	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	18,401	[1],[3]	33,794	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	12,771	[1],[3]	16,344	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,836	[1],[3]	2,131	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	10,201	[1],[3]	19,981	[1],[3]
Special Mention [Member] | On-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	0	[1],[3]	0	[1],[3]
Special Mention [Member] | Off-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	63,541	[1],[3]	83,121	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	8,255	[1],[3]	10,459	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	8,574	[1],[3]	5,068	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	35,532	[1],[3]	40,410	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	3,381	[1],[3]	3,220	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	7,201	[1],[3]	23,372	[1],[3]
Special Mention [Member] | Off-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	598	[1],[3]	592	[1],[3]
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	223,359	[1],[3]	186,514	[1],[3]
Substandard [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	52,168	[1],[3]	39,537	[1],[3]
Substandard [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	63,962	[1],[3]	50,353	[1],[3]
Substandard [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	48,505	[1],[3]	56,208	[1],[3]
Substandard [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	15,264	[1],[3]	17,801	[1],[3]
Substandard [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	42,336	[1],[3]	21,478	[1],[3]
Substandard [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,124	[1],[3]	1,137	[1],[3]
Substandard [Member] | On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	123,987	[1],[3]	91,132	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	31,306	[1],[3]	22,003	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	48,013	[1],[3]	29,647	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	13,667	[1],[3]	11,511	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	10,895	[1],[3]	12,660	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	19,991	[1],[3]	15,196	[1],[3]
Substandard [Member] | On-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	115	[1],[3]	115	[1],[3]
Substandard [Member] | Off-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	99,372	[1],[3]	95,382	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	20,862	[1],[3]	17,534	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	15,949	[1],[3]	20,706	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	34,838	[1],[3]	44,697	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	4,369	[1],[3]	5,141	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	22,345	[1],[3]	6,282	[1],[3]
Substandard [Member] | Off-balance sheet [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	$ 1,009	[1],[3]	$ 1,022	[1],[3]

[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.

[2] Includes loans and loans underlying Farm & Ranch Guaranteed Securities and LTSPCs that are 90 days or more past due, in foreclosure, restructured after delinquency, and in bankruptcy, excluding loans performing under either their original loan terms or a court-approved bankruptcy plan.

[3] Assets in the OAEM category generally have potential weaknesses due to performance issues but are currently considered to be adequately secured. Substandard assets have a well-defined weakness or weaknesses and there is a distinct possibility that some loss will be sustained if deficiencies are not corrected.