Loans and Allowance for Losses and Concentrations of Credit Risk - Loan (Details) - USD ($)		12 Months Ended
		Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Recovery		$ 45,000
Loans and Leases Receivable, Gross			$ 3,379,884,000	$ 3,258,413,000
Allowance for Loan and Lease Losses, Real Estate			5,415,000	4,480,000
Loans and Leases Receivable, Net Amount			4,507,435,000	3,962,044,000
Real Estate Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]		4,513,966,000	3,966,101,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums			(1,116,000)	423,000
Loans and Leases Receivable, Gross			4,512,850,000	3,966,524,000
Allowance for Loan and Lease Losses, Real Estate			5,415,000	4,480,000
Loans and Leases Receivable, Net Amount			4,507,435,000	3,962,044,000
Real Estate Loan [Member] | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			3,514,454,000	2,957,975,000
Real Estate Loan [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			999,512,000	1,008,126,000
Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]		3,381,000,000	3,257,990,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums			(1,116,000)	423,000
Loans and Leases Receivable, Gross			3,379,884,000	3,258,413,000
Allowance for Loan and Lease Losses, Real Estate			4,437,000	3,736,000
Loans and Leases Receivable, Net Amount			3,375,447,000	3,254,677,000
Unsecuritized [Member] | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			2,381,488,000	2,249,864,000
Unsecuritized [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			999,512,000	1,008,126,000
In Consolidated Trusts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]		1,132,966,000	708,111,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums			0	0
Loans and Leases Receivable, Gross			1,132,966,000	708,111,000
Allowance for Loan and Lease Losses, Real Estate			978,000	744,000
Loans and Leases Receivable, Net Amount			1,131,988,000	707,367,000
In Consolidated Trusts [Member] | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			1,132,966,000	708,111,000
In Consolidated Trusts [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance			$ 0	$ 0

[1] Unpaid principal balance is the basis of presentation in disclosures of outstanding balances for Farmer Mac's lines of business.