Loans and Allowance for Losses and Concentrations of Credit Risk - Loan (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, at amortized cost		$ 3,204,452	$ 3,258,413
Allowance for Loan and Lease Losses, Real Estate		4,529	4,480
Total loans, net of allowance		4,016,190	3,962,044
Unsecuritized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]	3,198,042	3,257,990
Unamortized premiums, discounts and other cost basis adjustments		6,410	423
Loans held for investment, at amortized cost		3,204,452	3,258,413
Allowance for Loan and Lease Losses, Real Estate		3,779	3,736
Total loans, net of allowance		3,200,673	3,254,677
Unsecuritized [Member] | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		2,206,191	2,249,864
Unsecuritized [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		991,851	1,008,126
In Consolidated Trusts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]	816,267	708,111
Unamortized premiums, discounts and other cost basis adjustments		0	0
Loans held for investment, at amortized cost		816,267	708,111
Allowance for Loan and Lease Losses, Real Estate		750	744
Total loans, net of allowance		815,517	707,367
In Consolidated Trusts | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		816,267	708,111
In Consolidated Trusts | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		0	0
Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance	[1]	4,014,309	3,966,101
Unamortized premiums, discounts and other cost basis adjustments		6,410	423
Loans held for investment, at amortized cost		4,020,719	3,966,524
Allowance for Loan and Lease Losses, Real Estate		4,529	4,480
Total loans, net of allowance		4,016,190	3,962,044
Loans [Member] | Farm & Ranch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		3,022,458	2,957,975
Loans [Member] | Rural Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Lease Receivable Unpaid Principal Balance		$ 991,851	$ 1,008,126

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