Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 26,086			$ 26,086			$ 24,951
Impaired Financing Receivable, with Related Allowance, Recorded Investment	60,401	[1]		60,401	[1]		72,116	[2]
Impaired Financing Receivable, Recorded Investment	86,487			86,487			97,067
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	26,190			26,190			24,733
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	59,742			59,742			70,308
Impaired Financing Receivable, Unpaid Principal Balance	85,932			85,932			95,041
Impaired Financing Receivable, Related Allowance	2,859			2,859			2,696
Financing Receivable, Recorded Investment, Nonaccrual Status	30,082	[3]		30,082	[3]		37,228	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	87,836		91,931	91,494		102,898
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	468		542	1,349		1,906
Crops [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,454			4,454			6,956
Impaired Financing Receivable, with Related Allowance, Recorded Investment	13,448	[1]		13,448	[1]		16,697	[2]
Impaired Financing Receivable, Recorded Investment	17,902			17,902			23,653
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,288			4,288			6,825
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,257			13,257			16,284
Impaired Financing Receivable, Unpaid Principal Balance	17,545			17,545			23,109
Impaired Financing Receivable, Related Allowance	426			426			406
Financing Receivable, Recorded Investment, Nonaccrual Status	4,656	[3]		4,656	[3]		10,812	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	19,975		27,311	21,873		29,570
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	90		248	365		651
Permanent Plantings [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	11,188			11,188			9,880
Impaired Financing Receivable, with Related Allowance, Recorded Investment	32,705	[1]		32,705	[1]		36,146	[2]
Impaired Financing Receivable, Recorded Investment	43,893			43,893			46,026
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	11,696			11,696			9,877
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	31,893			31,893			34,978
Impaired Financing Receivable, Unpaid Principal Balance	43,589			43,589			44,855
Impaired Financing Receivable, Related Allowance	1,781			1,781			1,702
Financing Receivable, Recorded Investment, Nonaccrual Status	14,972	[3]		14,972	[3]		15,237	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	43,280		37,340	44,144		42,041
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	142		169	412		666
Livestock [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	8,530			8,530			6,671
Impaired Financing Receivable, with Related Allowance, Recorded Investment	3,764	[1]		3,764	[1]		7,600	[2]
Impaired Financing Receivable, Recorded Investment	12,294			12,294			14,271
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,287			8,287			6,588
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	4,051			4,051			7,455
Impaired Financing Receivable, Unpaid Principal Balance	12,338			12,338			14,043
Impaired Financing Receivable, Related Allowance	291			291			193
Financing Receivable, Recorded Investment, Nonaccrual Status	4,414	[3]		4,414	[3]		5,344	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	12,305		15,252	13,040		16,579
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	149		38	284		230
Part-Time Farm [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,914			1,914			1,444
Impaired Financing Receivable, with Related Allowance, Recorded Investment	10,484	[1]		10,484	[1]		11,554	[2]
Impaired Financing Receivable, Recorded Investment	12,398			12,398			12,998
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,919			1,919			1,443
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	10,541			10,541			11,476
Impaired Financing Receivable, Unpaid Principal Balance	12,460			12,460			12,919
Impaired Financing Receivable, Related Allowance	361			361			392
Financing Receivable, Recorded Investment, Nonaccrual Status	6,040	[3]		6,040	[3]		5,835	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	12,276		11,909	12,407		13,053
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	87		87	288		359
Agriculture Storage and Processing [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		0	[2]
Impaired Financing Receivable, Recorded Investment	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Related Allowance	0			0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	0		0	0		1,084
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0	0		0
Other Commodity [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		119	[2]
Impaired Financing Receivable, Recorded Investment	0			0			119
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			115
Impaired Financing Receivable, Unpaid Principal Balance	0			0			115
Impaired Financing Receivable, Related Allowance	0			0			3
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	0		119	30		571
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0	0		0
Collateral Dependent Not Individually Analyzed [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, Recorded Investment	53,600			53,600			65,100
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, Related Allowance	1,400			1,400			1,300
Impaired Financing Receivable, Impairment analysis performed percent	62.00%	[1]		62.00%	[1]		67.00%
Less than 90 days past due [Member]
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 8,700	[3]		$ 8,700	[3]		$ 9,600	[4]

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $53.6 million (62 percent) of impaired loans as of September 30, 2014, which resulted in a specific reserve of $1.4 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $65.1 million (67 percent) of impaired loans as of December 31, 2013, which resulted in a specific reserve of $1.3 million.

[3] Includes $8.7 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.

[4] Includes $9.6 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.