Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Farmer Mac Guaranteed Securities and USDA Securities (Details) - USD ($) $ in Thousands			12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2016	Oct. 01, 2016
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Transfer of USDA Guaranteed Securities- Available-for-sale to Held-to-maturity; Unrealized holding gains				$ 73,100
Trading Securities [Abstract]
Transfer of Farmer Mac Guaranteed Securities - Available-for-sale to Held-to-maturity; Unrealized holding gains				700
Transfer of Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Available-for-sale to Held-to-maturity; Unrealized holding gains				$ 73,800
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	$ 66,124
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	4,137,688	$ 3,086,504	$ 3,086,504
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	4,203,812	3,158,456	3,158,456
Held to Maturity; Unrealized Holding Gains	5,992	7,192	7,192
Held to Maturity - Unrealized Holding Loss	(72,804)	(99,004)	(99,004)
Held-to-maturity Securities, Fair Value	4,137,000	3,066,644	3,066,644
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Amortized Cost Basis	5,295,564
Available-for-sale, at fair value	5,282,562
Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	(1,209)	(1,833)	(1,833)
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	2,138,995	1,151,064	1,151,064
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	2,137,786	1,149,231	1,149,231
Held to Maturity; Unrealized Holding Gains	5,992	7,192	7,192
Held to Maturity - Unrealized Holding Loss	(6,451)	(3,414)	(3,414)
Held-to-maturity Securities, Fair Value	2,137,327	1,153,009	1,153,009
USDA Securities [Member]
Trading Securities [Abstract]
Trading, at fair value	16,294	20,388	20,388
Institutional Credit [Member] | Farmer Mac Guaranteed Securities and USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)		71,952	71,952
Institutional Credit [Member] | Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	2,102,479	1,115,465	1,115,465
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	2,100,905	1,113,189	1,113,189
Held to Maturity; Unrealized Holding Gains	5,907	7,187	7,187
Held to Maturity - Unrealized Holding Loss	(5,968)	(3,175)	(3,175)
Held-to-maturity Securities, Fair Value	2,100,844	1,117,201	1,117,201
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	5,295,726	4,889,007	4,889,007
Available-for-sale Securities, Amortized Cost Basis	5,295,564	4,888,904	4,888,904
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	32,981	28,715	28,715
Available-for-sale Securities, Unrealized Losses	(45,983)	(63,934)	(63,934)
Available-for-sale, at fair value	5,282,562	4,853,685	4,853,685
Institutional Credit [Member] | Held-to-maturity Securities [Member] | Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	(1,574)	(2,276)	(2,276)
Institutional Credit [Member] | Available-for-sale Securities [Member] | Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	(162)	(103)	(103)
USDA Guarantees [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	400	400	400
USDA Guarantees [Member] | Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	36,516	35,599	35,599
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	36,881	36,042	36,042
Held to Maturity; Unrealized Holding Gains	85	5	5
Held to Maturity - Unrealized Holding Loss	(483)	(239)	(239)
Held-to-maturity Securities, Fair Value	36,483	35,808	35,808
USDA Guarantees [Member] | USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	67,333	73,785	73,785
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	1,998,693	1,935,440	1,935,440
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	2,066,026	2,009,225	2,009,225
Held to Maturity; Unrealized Holding Gains	0	0	0
Held to Maturity - Unrealized Holding Loss	(66,353)	(95,590)	(95,590)
Held-to-maturity Securities, Fair Value	1,999,673	1,913,635	1,913,635
Trading Securities [Abstract]
Trading Securities Unpaid Principal Balance	15,547	19,360	19,360
Trading Securities, Debt, Amortized Cost	16,727	20,737	20,737
Trading Securities, Unrealized Gains	61	41
Trading Securities, Unrealized Holding Loss	(494)	(390)
Trading, at fair value	16,294	20,388	20,388
USDA Guarantees [Member] | Available-for-sale Securities [Member] | Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	365	443	443
USDA Guarantees [Member] | Trading Securities [Member] | USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	$ 1,180	$ 1,377	1,377
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities [Member] | USDA Guarantee [Member] | Available-for-sale Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			2,000,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Farmer Mac Guaranteed Securities [Member] | Farmer Mac Guaranteed Securities [Member] | Available-for-sale Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			$ 32,800