Loans and Allowance for Losses and Concentrations of Credit Risk - Financing Receivables Credit Quality Indicators (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	$ 5,347,248	[1],[2]	$ 5,417,174	[1],[2]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	32,101	[1]	18,917	[3]
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	5,115,357	[1]	5,172,691	[1]
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	95,195	[1],[4]	111,888	[1],[4]
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	136,696	[1],[5]	132,595	[1],[5]
On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,570,912	[1]	2,540,222	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	30,151	[1]	18,427	[3]
On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,449,530	[1]	2,419,285	[1]
On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	46,655	[1],[4]	54,495	[1],[4]
On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	74,727	[1],[5]	66,442	[1],[5]
Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,776,336	[1]	2,876,952	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	1,950	[1]	490	[3]
Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,665,827	[1]	2,753,406	[1]
Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	48,540	[1],[4]	57,393	[1],[4]
Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	61,969	[1],[5]	66,153	[1],[5]
Crops [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,928,976	[1]	2,941,266	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	3,817	[1]	4,175	[3]
Crops [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	2,872,721	[1]	2,887,319	[1]
Crops [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	27,005	[1],[4]	30,417	[1],[4]
Crops [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	29,250	[1],[5]	23,530	[1],[5]
Crops [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,661,202	[1]	1,633,667	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,406	[1]	4,175	[3]
Crops [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,629,509	[1]	1,604,546	[1]
Crops [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	12,987	[1],[4]	16,814	[1],[4]
Crops [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	18,706	[1],[5]	12,307	[1],[5]
Crops [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,267,774	[1]	1,307,599	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	1,411	[1]	0	[3]
Crops [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,243,212	[1]	1,282,773	[1]
Crops [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	14,018	[1],[4]	13,603	[1],[4]
Crops [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	10,544	[1],[5]	11,223	[1],[5]
Permanent Plantings [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	909,088	[1]	920,195	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	21,967	[1]	6,869	[3]
Permanent Plantings [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	846,402	[1]	856,901	[1]
Permanent Plantings [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	15,814	[1],[4]	18,180	[1],[4]
Permanent Plantings [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	46,872	[1],[5]	45,114	[1],[5]
Permanent Plantings [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	405,410	[1]	395,421	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	21,967	[1]	6,869	[3]
Permanent Plantings [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	361,875	[1]	353,487	[1]
Permanent Plantings [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	4,181	[1],[4]	6,030	[1],[4]
Permanent Plantings [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	39,354	[1],[5]	35,904	[1],[5]
Permanent Plantings [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	503,678	[1]	524,774	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Permanent Plantings [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	484,527	[1]	503,414	[1]
Permanent Plantings [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	11,633	[1],[4]	12,150	[1],[4]
Permanent Plantings [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	7,518	[1],[5]	9,210	[1],[5]
Livestock [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,221,734	[1]	1,260,618	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	3,014	[1]	5,045	[3]
Livestock [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,146,597	[1]	1,174,057	[1]
Livestock [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	50,403	[1],[4]	61,320	[1],[4]
Livestock [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	24,734	[1],[5]	25,241	[1],[5]
Livestock [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	408,656	[1]	412,620	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	2,517	[1]	4,555	[3]
Livestock [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	373,623	[1]	375,010	[1]
Livestock [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	28,855	[1],[4]	31,039	[1],[4]
Livestock [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	6,178	[1],[5]	6,571	[1],[5]
Livestock [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	813,078	[1]	847,998	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	497	[1]	490	[3]
Livestock [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	772,974	[1]	799,047	[1]
Livestock [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	21,548	[1],[4]	30,281	[1],[4]
Livestock [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	18,556	[1],[5]	18,670	[1],[5]
Part-Time Farm [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	169,417	[1]	173,954	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	3,303	[1]	2,828	[3]
Part-Time Farm [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	151,840	[1]	154,931	[1]
Part-Time Farm [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,965	[1],[4]	1,963	[1],[4]
Part-Time Farm [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	15,612	[1],[5]	17,060	[1],[5]
Part-Time Farm [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	68,484	[1]	69,511	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	3,261	[1]	2,828	[3]
Part-Time Farm [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	57,363	[1]	57,239	[1]
Part-Time Farm [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	632	[1],[4]	612	[1],[4]
Part-Time Farm [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	10,489	[1],[5]	11,660	[1],[5]
Part-Time Farm [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	100,933	[1]	104,443	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	42	[1]	0	[3]
Part-Time Farm [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	94,477	[1]	97,692	[1]
Part-Time Farm [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,333	[1],[4]	1,351	[1],[4]
Part-Time Farm [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	5,123	[1],[5]	5,400	[1],[5]
Agriculture Storage and Processing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	110,367	[1]	114,360	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Agriculture Storage and Processing [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	90,787	[1]	93,366	[1]
Agriculture Storage and Processing [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[4]	0	[1],[4]
Agriculture Storage and Processing [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	19,580	[1],[5]	20,994	[1],[5]
Agriculture Storage and Processing [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	25,800	[1]	29,003	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Agriculture Storage and Processing [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	25,800	[1]	29,003	[1]
Agriculture Storage and Processing [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[4]	0	[1],[4]
Agriculture Storage and Processing [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[5]	0	[1],[5]
Agriculture Storage and Processing [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	84,567	[1]	85,357	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Agriculture Storage and Processing [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	64,987	[1]	64,363	[1]
Agriculture Storage and Processing [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[4]	0	[1],[4]
Agriculture Storage and Processing [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	19,580	[1],[5]	20,994	[1],[5]
Other Commodity [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	7,666	[1]	6,781	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Other Commodity [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	7,010	[1]	6,117	[1]
Other Commodity [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	8	[1],[4]	8	[1],[4]
Other Commodity [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	648	[1],[5]	656	[1],[5]
Other Commodity [Member] | On-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,360	[1]	0	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Other Commodity [Member] | On-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	1,360	[1]	0	[1]
Other Commodity [Member] | On-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[4]	0	[1],[4]
Other Commodity [Member] | On-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	0	[1],[5]	0	[1],[5]
Other Commodity [Member] | Off-balance sheet [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	6,306	[1]	6,781	[1]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	0	[1]	0	[3]
Other Commodity [Member] | Off-balance sheet [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	5,650	[1]	6,117	[1]
Other Commodity [Member] | Off-balance sheet [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	8	[1],[4]	8	[1],[4]
Other Commodity [Member] | Off-balance sheet [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Gross	$ 648	[1],[5]	$ 656	[1],[5]

[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] Geographic regions: Northwest (AK, ID, MT, OR, WA, WY); Southwest (AZ, CA, CO, HI, NM, NV, UT); Mid-North (IA, IL, IN, MI, MN, NE, ND, SD, WI); Mid-South (AR, KS, LA, MO, OK, TX); Northeast (CT, DE, KY, MA, MD, ME, NH, NJ, NY, OH, PA, RI, VA, VT, WV); Southeast (AL, FL, GA, MS, NC, SC, TN).

[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.

[4] Assets in the Special mention category generally have potential weaknesses due to performance issues but are currently considered to be adequately secured.

[5] 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.