Loans and Allowance for Losses and Concentrations of Credit Risk - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 20,200			$ 20,200			$ 23,607
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	20,170			20,170			23,562
Impaired Financing Receivable, with Related Allowance, Recorded Investment	57,659	[1]		57,659	[1]		52,115	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	57,690			57,690			52,133
Impaired Financing Receivable, Recorded Investment	77,859			77,859			75,722
Impaired Financing Receivable, Unpaid Principal Balance	77,860			77,860			75,695
Impaired Financing Receivable, Related Allowance	1,952			1,952			1,850
Financing Receivable, Recorded Investment, Nonaccrual Status	26,571	[3]		26,571	[3]		41,672	[4]
Impaired Financing Receivable, Average Recorded Investment	76,304		$ 101,067	80,596		$ 94,434
Impaired Financing Receivable, Interest Income, Cash Basis Method	437		419	1,377		1,331
Crops [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	6,851			6,851			3,772
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	6,838			6,838			3,720
Impaired Financing Receivable, with Related Allowance, Recorded Investment	29,985	[1]		29,985	[1]		15,103	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	29,949			29,949			15,020
Impaired Financing Receivable, Recorded Investment	36,836			36,836			18,875
Impaired Financing Receivable, Unpaid Principal Balance	36,787			36,787			18,740
Impaired Financing Receivable, Related Allowance	769			769			476
Financing Receivable, Recorded Investment, Nonaccrual Status	7,964	[3]		7,964	[3]		5,105	[4]
Impaired Financing Receivable, Average Recorded Investment	33,032		27,133	28,293		23,176
Impaired Financing Receivable, Interest Income, Cash Basis Method	46		33	108		373
Permanent Plantings [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	9,217			9,217			12,340
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,204			9,204			12,346
Impaired Financing Receivable, with Related Allowance, Recorded Investment	11,494	[1]		11,494	[1]		11,939	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	11,474			11,474			11,938
Impaired Financing Receivable, Recorded Investment	20,711			20,711			24,279
Impaired Financing Receivable, Unpaid Principal Balance	20,678			20,678			24,284
Impaired Financing Receivable, Related Allowance	504			504			360
Financing Receivable, Recorded Investment, Nonaccrual Status	9,859	[3]		9,859	[3]		16,546	[4]
Impaired Financing Receivable, Average Recorded Investment	22,980		37,911	25,277		39,337
Impaired Financing Receivable, Interest Income, Cash Basis Method	236		234	789		459
Livestock [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,423			2,423			5,644
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,422			2,422			5,645
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,993	[1]		9,993	[1]		9,050	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	10,090			10,090			9,153
Impaired Financing Receivable, Recorded Investment	12,416			12,416			14,694
Impaired Financing Receivable, Unpaid Principal Balance	12,512			12,512			14,798
Impaired Financing Receivable, Related Allowance	524			524			787
Financing Receivable, Recorded Investment, Nonaccrual Status	3,292	[3]		3,292	[3]		4,313	[4]
Impaired Financing Receivable, Average Recorded Investment	12,120		12,534	13,704		13,923
Impaired Financing Receivable, Interest Income, Cash Basis Method	81		76	229		273
Part-Time Farm [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,709			1,709			1,851
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,706			1,706			1,851
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,187	[1]		6,187	[1]		6,185	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,177			6,177			6,184
Impaired Financing Receivable, Recorded Investment	7,896			7,896			8,036
Impaired Financing Receivable, Unpaid Principal Balance	7,883			7,883			8,035
Impaired Financing Receivable, Related Allowance	155			155			227
Financing Receivable, Recorded Investment, Nonaccrual Status	5,456	[3]		5,456	[3]		5,870	[4]
Impaired Financing Receivable, Average Recorded Investment	8,172		9,989	8,654		11,248
Impaired Financing Receivable, Interest Income, Cash Basis Method	74		76	251		226
Agriculture Storage and Processing [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		9,838	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			9,838
Impaired Financing Receivable, Recorded Investment	0			0			9,838
Impaired Financing Receivable, Unpaid Principal Balance	0			0			9,838
Impaired Financing Receivable, Related Allowance	0			0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		9,838	[4]
Impaired Financing Receivable, Average Recorded Investment	0		13,500	4,668		6,750
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0	0		0
Other Commodity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0			0			0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]		0	[1]		0	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Recorded Investment	0			0			0
Impaired Financing Receivable, Unpaid Principal Balance	0			0			0
Impaired Financing Receivable, Related Allowance	0			0			0
Financing Receivable, Recorded Investment, Nonaccrual Status	0	[3]		0	[3]		0	[4]
Impaired Financing Receivable, Average Recorded Investment	0		0	0		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		$ 0	0		$ 0
Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	55,500			55,500			46,400
Impaired Financing Receivable, Related Allowance	$ 1,300			$ 1,300			$ 1,000
Impaired Financing Receivable, Impairment analysis performed percent	71.00%			71.00%			61.00%
Less than 90 days past due [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 10,600	[3]		$ 10,600	[3]		$ 14,700	[4]

[1] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $55.5 million (71 percent) of impaired loans as of September 30, 2016, which resulted in a specific allowance of $1.3 million.

[2] Impairment analysis was performed in the aggregate in consideration of similar risk characteristics of the assets and historical statistics on $46.4 million (61 percent) of impaired loans as of December 31, 2015, which resulted in a specific allowance of $1.0 million.

[3] Includes $10.6 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.

[4] Includes $14.7 million of loans that are less than 90 days delinquent but which have not met Farmer Mac's performance criteria for returning to accrual status.