Accounting Policies - Cash and Cash Equivalents and Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 02, 2014	Jan. 01, 2013
Other Significant Noncash Transactions [Line Items]
Interest Paid							$ 108,254	$ 171,644	$ 114,609
Income Taxes Paid							31,000	12,750	23,000
Non-cash activity:
Real estate owned acquired through loan liquidation							0	0	1,443
Proceeds from sale of Farmer Mac Guaranteed Securities							336,913	175,754	150,417
Consolidation of Farm & Ranch Guaranteed Securities from off-balance sheet to loans held for investment in consolidated trusts and to debt securities of consolidated trusts held by third parties							336,913	199,906	150,417
Purchases of securities - traded, not yet settled							20,000	70,178	0
Issuance Costs on the retirement of Farmer Mac II LLC Preferred Stock	$ 0	$ 0	$ 0	$ 8,147			8,147	0	0
Unsettled common stock repurchases							197	0	0
Transfers of loans held for sale to loans held for investment							0	0	673,991
Transfer of Farmer Mac Guaranteed Securities - Available-for-sale to Held-to-maturity; Unrealized holding gains										$ 22,300
Transfer of Loans Held-for-sale to Loans Held-for Investment, unamortized discount											$ (5,900)
Institutional Credit [Member]
Non-cash activity:
Issuance Costs on the retirement of Farmer Mac II LLC Preferred Stock							0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Non-cash activity:
Transfers of available-for-sale Farmer Mac Guaranteed Securities to held-to-maturity								1,632,786
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities [Member] | Available-for-sale Securities [Member]
Non-cash activity:
Transfers of available-for-sale Farmer Mac Guaranteed Securities to held-to-maturity								1,632,786
Fair Value, Inputs, Level 3 [Member] | Institutional Credit [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities [Member] | Available-for-sale Securities [Member]
Non-cash activity:
Transfers of available-for-sale Farmer Mac Guaranteed Securities to held-to-maturity					$ 0	$ 1,600,000	$ 0	$ 1,632,786	$ 0