Loans and Allowance for Losses and Concentrations of Credit Risk Impaired Financing Receivables (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 111,334		$ 102,033	$ 107,673		$ 97,475
Impaired Financing Receivable, Recorded Investment	95,282			95,282			100,351
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	34,628			34,628			30,638
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	34,185			34,185			30,236
Impaired Financing Receivable, with Related Allowance, Recorded Investment	60,654	[1]		60,654	[1]		69,713	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	58,999			58,999			68,601
Impaired Financing Receivable, Unpaid Principal Balance	93,184			93,184			98,837
Impaired Financing Receivable, Related Allowance	2,490			2,490			6,659
Financing Receivable, Recorded Investment, Nonaccrual Status	42,815	[3]		42,815	[3]		45,335	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	300		586	1,364		1,107
Crops [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	34,879		27,873	31,422		28,521
Impaired Financing Receivable, Recorded Investment	30,606			30,606			24,509
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,475			7,475			7,295
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	7,369			7,369			7,247
Impaired Financing Receivable, with Related Allowance, Recorded Investment	23,131	[1]		23,131	[1]		17,214	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	22,019			22,019			16,829
Impaired Financing Receivable, Unpaid Principal Balance	29,388			29,388			24,076
Impaired Financing Receivable, Related Allowance	520			520			706
Financing Receivable, Recorded Investment, Nonaccrual Status	10,512	[3]		10,512	[3]		11,888	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	61		64	403		141
Permanent Plantings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	46,300		35,012	43,606		32,925
Impaired Financing Receivable, Recorded Investment	37,333			37,333			38,219
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	15,845			15,845			11,652
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	15,702			15,702			11,509
Impaired Financing Receivable, with Related Allowance, Recorded Investment	21,488	[1]		21,488	[1]		26,567	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	21,054			21,054			26,095
Impaired Financing Receivable, Unpaid Principal Balance	36,756			36,756			37,604
Impaired Financing Receivable, Related Allowance	1,468			1,468			1,515
Financing Receivable, Recorded Investment, Nonaccrual Status	19,373	[3]		19,373	[3]		15,789	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	123		376	497		676
Livestock [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	17,403		16,036	17,270		14,118
Impaired Financing Receivable, Recorded Investment	15,998			15,998			17,004
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	9,644			9,644			7,644
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,460			9,460			7,489
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,354	[1]		6,354	[1]		9,360	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,305			6,305			9,219
Impaired Financing Receivable, Unpaid Principal Balance	15,765			15,765			16,708
Impaired Financing Receivable, Related Allowance	162			162			355
Financing Receivable, Recorded Investment, Nonaccrual Status	6,229	[3]		6,229	[3]		5,141	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	38		63	192		116
Part-Time Farm [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	12,181		17,671	13,207		15,992
Impaired Financing Receivable, Recorded Investment	11,226			11,226			15,258
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,664			1,664			3,140
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,654			1,654			3,090
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,562	[1]		9,562	[1]		12,118	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	9,506			9,506			12,007
Impaired Financing Receivable, Unpaid Principal Balance	11,160			11,160			15,097
Impaired Financing Receivable, Related Allowance	338			338			682
Financing Receivable, Recorded Investment, Nonaccrual Status	6,701	[3]		6,701	[3]		8,180	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	78		83	272		174
Agriculture Storage and Processing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	0		4,400	1,446		4,880
Impaired Financing Receivable, Recorded Investment	0			0			4,337
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		4,337	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			4,337
Impaired Financing Receivable, Unpaid Principal Balance	0			0			4,337
Impaired Financing Receivable, Related Allowance	0			0			3,400
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		4,337	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	0		0	0		0
Other Commodity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	571		1,041	722		1,039
Impaired Financing Receivable, Recorded Investment	119			119			1,024
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			907
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			901
Impaired Financing Receivable, with Related Allowance, Recorded Investment	119	[1]		119	[1]		117	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	115			115			114
Impaired Financing Receivable, Unpaid Principal Balance	115			115			1,015
Impaired Financing Receivable, Related Allowance	2			2			1
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Interest Income, Accrual Method	0		0	0		0
Less than 90 days past due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	15,300	[3]		15,300	[3]		15,700	[4]
Collateral Dependent Not Individually Analyzed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Recorded Investment	53,400			53,400			56,000	[2]
Impaired Financing Receivable, Impairment analysis performed percent	56.00%	[1]		56.00%	[1]		56.00%	[2]
Impaired Financing Receivable, Related Allowance	$ 1,100	[1]		$ 1,100	[1]		$ 1,100

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $53.4 million (56 percent) of impaired loans as of June 30, 2013, which resulted in a specific reserve of $1.1 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $56.0 million (56 percent) of impaired loans as of December 31, 2012, which resulted in a specific reserve of $1.1 million.

[3] Includes $15.3 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 $15.7 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.