Related Party Transactions - National Rural Utilities Cooperative Finance Corporation (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Common Stock Ownership Percentage by a Related Party	5.00%
CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	$ 903,465,000	$ 906,965,000	$ 549,523,000
Related Party Transaction, Related Party's percent of total Program	32.70%	29.40%	18.60%
Related Party's percent of Farmer Mac Total Outstanding Book of Business	18.70%	18.60%
Accounts Receivable, Related Parties, Current	300,000	700,000	700,000
Revenue from Related Parties	3,200,000	4,100,000	4,400,000
Due from Related Parties	900,000	5,600,000
Interest Income, Related Party	12,700,000	23,700,000	28,000,000
Related Party Transaction, Expenses from Transactions with Related Party	3,400,000	3,352,000	3,000,000
Common Class A, Voting [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Common Stock Ownership Percentage by a Related Party	7.90%
Rural Utilities [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Related Party's percent of total Program	100.00%	100.00%	100.00%
Rural Utilities [Member] \| Loans Collateralized by Real Estate [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	75,500,000	86,965,000	166,117,000
Institutional Credit [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Related Party's percent of total Program	64.70%	64.40%	38.90%
Farmer Mac Guaranteed Securities [Member] \| On-balance sheet [Member] \| Institutional Credit [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	820,775,000	820,000,000	383,406,000
Farmer Mac Guaranteed Securities [Member] \| Off-balance sheet [Member] \| Institutional Credit [Member] \| CFC [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	$ 7,190,000	$ 0	$ 0

Common Stock Ownership Percentage by a Related Party

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Related Party's percent of Farmer Mac Total Outstanding Book of Business

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Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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Amount of interest income earned from interest-bearing assets owed to the entity by related party.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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