CONSOLIDATED STATEMENTS OF EQUITY Statement - USD ($)	Total	Common Class C, Non-Voting [Member]	Preferred Stock [Member]	Preferred Stock [Member] Common Class C, Non-Voting [Member]	Common Stock [Member]	Common Stock [Member] Common Class C, Non-Voting [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Common Class C, Non-Voting [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Common Class C, Non-Voting [Member]	Retained Earnings [Member]	Retained Earnings [Member] Common Class C, Non-Voting [Member]	Noncontrolling Interest [Member]	Noncontrolling Interest [Member] Common Class C, Non-Voting [Member]
Beginning Balance (Shares Outstanding) at Dec. 31, 2015			8,400,000		10,687,000
Beginning Balance at Dec. 31, 2015	$ 553,720,000		$ 204,759,000		$ 10,687,000		$ 117,862,000		$ (11,019,000)		$ 231,228,000		$ 203,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Attributable to Farmer Mac	48,573,000		0		0		0		0		48,573,000		0
Less: Net loss attributable to non-controlling interest	62,000		0		0		0		0		0		(62,000)
Other comprehensive income, net of tax	24,583,000		0		0		0		24,583,000		0		0
Preferred stock	(9,886,000)		0		0		0		0		(9,886,000)		0
Common stock	(8,145,000)		0		0		0		0		(8,145,000)		0
Stock Issued During Period, Shares, New Issues				0		101,000
Stock Issued During Period, Value, New Issues		$ 491,000		$ 0		$ 101,000		$ 390,000		$ 0		$ 0		$ 0
Repurchase of Class C Common Stock				0		(307,000)
Repurchase of Class C Common Stock		(9,088,000)		$ 0		$ (307,000)		0		0		(8,781,000)		0
Stock-based compensation cost	2,566,000		0		0		2,566,000		0		0		0
Other stock-based award activity	(1,921,000)		0		0		(1,921,000)		0		0		0
Redemption of interest in subsidiary	53,000		$ 0		$ 0		0		0		0		53,000
Ending Balance (Shares Outstanding) at Sep. 30, 2016			8,400,000		10,481,000
Ending Balance at Sep. 30, 2016	600,884,000		$ 204,759,000		$ 10,481,000		118,897,000		13,564,000		252,989,000		194,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock	(0.26)
Ending Balance (Shares Outstanding) at Dec. 31, 2016			8,400,000		10,539,000
Ending Balance at Dec. 31, 2016	643,647,000		$ 204,759,000		$ 10,539,000		118,655,000		33,758,000		275,714,000		222,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Attributable to Farmer Mac	64,476,000		0		0		0		0		64,476,000		0
Less: Net loss attributable to non-controlling interest	165,000		0		0		0		0		0		(165,000)
Other comprehensive income, net of tax	7,037,000		0		0		0		7,037,000		0		0
Preferred stock	(9,886,000)		0		0		0		0		(9,886,000)		0
Common stock	(11,435,000)		0		0		0		0		(11,435,000)		0
Stock Issued During Period, Shares, New Issues				0		74,000
Stock Issued During Period, Value, New Issues		$ 302,000		$ 0		$ 74,000		$ 228,000		$ 0		$ 0		$ 0
Repurchase of Class C Common Stock		(668,000)
Stock-based compensation cost	2,597,000		0		0		2,597,000		0		0		0
Other stock-based award activity	(2,350,000)		0		0		(2,350,000)		0		0		0
Redemption of interest in subsidiary	(57,000)		$ 0		$ 0		0		0		0		(57,000)
Ending Balance (Shares Outstanding) at Sep. 30, 2017			8,400,000		10,613,000
Ending Balance at Sep. 30, 2017	$ 694,166,000		$ 204,759,000		$ 10,613,000		$ 119,130,000		$ 40,795,000		$ 318,869,000		$ 0