Business Segment Reporting - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 segment	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of reportable segments	3
Debt outstanding	$ 11,602,105,000	$ 10,192,761,000
Farmer Mac II [Member]
Segment Reporting Information [Line Items]
Assets at fair value	1,700,000,000
Debt outstanding	328,000,000
Preferred Stock outstanding	250,000,000
Common Stock outstanding	$ 1,000,000,000