Loans and Allowance for Losses and Concentrations of Credit Risk - Concentrations of Credit Risk (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	$ 5,310,664	[1]	$ 5,163,080	[1]
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,832,785	[1]	2,666,857	[1]
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	906,802	[1]	907,824	[1]
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,256,829	[1]	1,246,105	[1]
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	158,226	[1]	162,743	[1]
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	147,840	[1]	170,918	[1]
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	8,182	[1]	8,633	[1]
Commodity and Collateral Type Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	5,310,664		5,163,080
Commodity and Collateral Type Risk [Member] | Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	2,832,785		2,666,857
Commodity and Collateral Type Risk [Member] | Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	906,802		907,824
Commodity and Collateral Type Risk [Member] | Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,256,829		1,246,105
Commodity and Collateral Type Risk [Member] | Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	158,226		162,743
Commodity and Collateral Type Risk [Member] | Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	147,840		170,918
Commodity and Collateral Type Risk [Member] | Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	8,182		8,633
Geographic Concentration Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	5,310,664	[2]	5,163,080	[2]
Geographic Concentration Risk [Member] | Northwest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	551,254	[2]	524,034	[2]
Geographic Concentration Risk [Member] | Southwest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,716,331	[2]	1,752,109	[2]
Geographic Concentration Risk [Member] | Mid-North [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,834,187	[2]	1,702,668	[2]
Geographic Concentration Risk [Member] | Mid-South [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	622,183	[2]	601,359	[2]
Geographic Concentration Risk [Member] | Northeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	224,830	[2]	231,731	[2]
Geographic Concentration Risk [Member] | Southeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	361,879	[2]	351,179	[2]
Original Loan To Value Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	5,310,664		5,163,080
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range One [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,439,917		1,375,758
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	0.00%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	40.00%
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range Two [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,160,478		1,099,033
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	40.01%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	50.00%
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range Three [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,462,113		1,431,562
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	50.01%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	60.00%
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range Four [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	1,107,922		1,113,427
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	60.01%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	70.00%
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range Five [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	106,556		110,828
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	70.01%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	80.00%
Original Loan To Value Risk [Member] | Financing Receivables, Original Loan-To-Value Ratio, Range Six [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Gross	$ 33,678		$ 32,472
Financing Receivables, Loan-To-Value Ratio Range, Lower Range Limit	80.01%
Financing Receivables, Loan-To-Value Ratio Range, Upper Range Limit	90.00%

[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).