Accounting Policies - Variable Interest Entities (Details) (USD $)	Dec. 31, 2012		Dec. 31, 2011
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	$ 563,575,000		$ 1,121,559,000
Debt securities of consolidated trusts held by third parties	167,621,000		701,583,000
Debt Instrument, Unamortized Premium	35,100,000		39,500,000
Other Liabilities	7,200,000		4,800,000
Shared power with unrelated party [Member] | Farmer Mac I [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	911,400,000		621,900,000
On-balance sheet [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	563,575,000	[1]	1,121,559,000	[1]
Debt securities of consolidated trusts held by third parties	167,621,000	[2]	701,583,000	[2]
On-balance sheet [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	58,051,000	[3]	66,563,000	[3]
Variable interest entity maximum loss exposure	56,238,000	[4]	65,410,000	[4]
On-balance sheet [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	724,893,000		771,162,000
Variable interest entity maximum loss exposure	737,148,000	[4]	788,381,000	[4]
On-balance sheet [Member] | Farmer Mac I [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	160,436,000	[1]	696,735,000	[1]
Debt securities of consolidated trusts held by third parties	167,621,000	[2]	701,583,000	[2]
On-balance sheet [Member] | Farmer Mac I [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	31,370,000	[3]	30,964,000	[3]
Variable interest entity maximum loss exposure	30,000,000	[4]	30,000,000	[4]
On-balance sheet [Member] | Farmer Mac I [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0		0
Variable interest entity maximum loss exposure	0	[4]	0	[4]
On-balance sheet [Member] | Farmer Mac II [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	0	[1]	0	[1]
Debt securities of consolidated trusts held by third parties	0	[2]	0	[2]
On-balance sheet [Member] | Farmer Mac II [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	26,681,000	[3]	35,599,000	[3]
Variable interest entity maximum loss exposure	26,238,000	[4]	35,410,000	[4]
On-balance sheet [Member] | Farmer Mac II [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0		0
Variable interest entity maximum loss exposure	0	[4]	0	[4]
On-balance sheet [Member] | Rural Utilities [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	403,139,000	[1]	424,824,000	[1]
Debt securities of consolidated trusts held by third parties	0	[2]	0	[2]
On-balance sheet [Member] | Rural Utilities [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[3]	0	[3]
Variable interest entity maximum loss exposure	0	[4]	0	[4]
On-balance sheet [Member] | Rural Utilities [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0		0
Variable interest entity maximum loss exposure	0	[4]	0	[4]
On-balance sheet [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trust, at amortized cost	0	[1]	0	[1]
Debt securities of consolidated trusts held by third parties	0	[2]	0	[2]
On-balance sheet [Member] | Investments [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	[3]	0	[3]
Variable interest entity maximum loss exposure	0	[4]	0	[4]
On-balance sheet [Member] | Investments [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	724,893,000		771,162,000
Variable interest entity maximum loss exposure	737,148,000	[4]	788,381,000	[4]
Off-balance sheet [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	1,911,028,000	[4],[5]	1,633,959,000	[4],[5]
Off-balance sheet [Member] | Farmer Mac I [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	1,881,370,000	[4],[5]	1,591,871,000	[4],[5]
Off-balance sheet [Member] | Farmer Mac II [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	29,658,000	[4],[5]	42,088,000	[4],[5]
Off-balance sheet [Member] | Rural Utilities [Member] | Farmer Mac Guaranteed Securities Trusts [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	0	[4],[5]	0	[4],[5]
Off-balance sheet [Member] | Investments [Member] | Investment Securities Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Variable interest entity maximum loss exposure	0	[4],[5]	0	[4],[5]
Farmer Mac II [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net	400,000		200,000
Farmer Mac I [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Discount (Premium), Net	1,400,000		1,000,000
Rural Utilities [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Unamortized Premium	$ 34,300,000		$ 38,000,000

[1] Includes unamortized premiums related to Rural Utilities of $34.3 million.

[2] Includes borrower remittances of $7.2 million, which have not been passed through to third party investors as of December 31, 2012.

[3] Includes unamortized premiums and discounts and fair value adjustments related to Farm & Ranch and USDA Guarantees of $1.4 million and $0.4 million, respectively.

[4] Farmer Mac uses unpaid principal balance and outstanding face amount of investment securities to represent maximum exposure to loss.

[5] f the Farm & Ranch amount, $911.4 million relates to unconsolidated trusts where Farmer Mac determined it was not the primary beneficiary due to shared power with an unrelated party. Consolidation of Variable Interest Entities December 31, 2011 Farm & Ranch USDA Guarantees Rural Utilities Investments Total (in thousands)On-Balance Sheet: Consolidated VIEs: Loans held for investment in consolidated trusts, at amortized cost (1)$696,735 $— $424,824 $— $1,121,559Debt securities of consolidated trusts held by third parties (2)701,583 — — — 701,583 Unconsolidated VIEs: Farmer Mac Guaranteed Securities: Carrying value (3)30,964 35,599 — — 66,563 Maximum exposure to loss (4)30,000 35,410 — — 65,410 Investment securities: Carrying value— — — 771,162 771,162 Maximum exposure to loss (4)— — — 788,381 788,381Off-Balance Sheet: Unconsolidated VIEs: Farmer Mac Guaranteed Securities: Maximum exposure to loss (4) (5)1,591,871 42,088 — — 1,633,959