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Financial Derivatives - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral, Obligation to Return Cash | $ 700,000 |  |  |  |  |  |  |  | $ 700,000 |  |
Farmer Mac Guaranteed Securities and USDA Securities |  |  |  |  |  |  |  |  | 290,953,000 | $ 203,796,000 | $ 150,281,000
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | 9,955,745,000 |  |  |  | $ 8,860,296,000 |  |  |  | 9,955,745,000 | 8,860,296,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 7,487,000 |  |  |  | 7,093,000 |  |  |  | 7,487,000 | 7,093,000 |
Financial derivatives, at fair value | (19,633,000) |  |  |  | (26,599,000) |  |  |  | (19,633,000) | (26,599,000) |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Collateral Pledged | 47,018,000 |  |  |  | 24,926,000 |  |  |  | 47,018,000 | 24,926,000 |
Derivative Asset | 5,709,000 |  |  |  | 7,093,000 |  |  |  | 5,709,000 | 7,093,000 |
Loans |  |  |  |  |  |  |  |  | 198,152,000 | 162,150,000 | 134,577,000
Total interest expense | (104,237,000) | $ (97,557,000) | $ (91,737,000) | $ (76,317,000) | (70,088,000) | $ (64,935,000) | $ (58,316,000) | $ (49,546,000) | (369,848,000) | (242,885,000) | (171,626,000)
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 3,687,000 | (753,000) | (2,311,000)
TotalAmountsofLineItemsPresentedintheConsolidatedStatementofIncome |  |  |  |  |  |  |  |  | 115,570,000 | 123,814,000 | 115,543,000
Derivative Liability | 27,385,000 |  |  |  | 1,673,000 |  |  |  | 27,385,000 | 1,673,000 |
Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | 9,900,000,000 |  |  |  | 8,800,000,000 |  |  |  | 9,900,000,000 | 8,800,000,000 |
Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Income_Expense related to interest settlements on fair value hedges |  |  |  |  |  |  |  |  | 27,253,000 | 26,295,000 | 20,859,000
Gain (Loss) on Fair Value Hedges Recognized in Earnings |  |  |  |  |  |  |  |  | 4,941,000 | (719,000) | 5,043,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness |  |  |  |  |  |  |  |  |  | (320,000) | (353,000)
Fair Value Hedging [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Components Included from Assessment of Interest Rate Fair Value Hedge Effectiveness |  |  |  |  |  |  |  |  |  | 100,000 | (5,200,000)
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Net Interest Settlements |  |  |  |  |  |  |  |  | (6,764,000) | (8,845,000) | (16,373,000)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net |  |  |  |  |  |  |  |  |  | (600,000) | (200,000)
Cash Flow Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | (6,000) | (5,000) | (1,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax |  |  |  |  |  |  |  |  | 316,000 | (1,974,000) | (2,126,000)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item |  |  |  |  |  |  |  |  | (9,182,000) | (4,133,000) | (1,437,000)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments |  |  |  |  |  |  |  |  | (8,872,000) | (6,432,000) | (3,917,000)
Cash [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral, Obligation to Return Cash |  |  |  |  | 0 |  |  |  |  | 0 |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Obligation to Return Securities Received as Collateral | 1,778,000 |  |  |  |  |  |  |  | 1,778,000 |  |
Collateral Pledged | 0 |  |  |  | 100,000 |  |  |  | 0 | 100,000 |
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Hedged Item Net Interest Settlements |  |  |  |  |  |  |  |  | 34,685,000 | 35,485,000 | 37,232,000
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | (668,000) | (345,000) | 0
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest Rate Swap, Pay Fixed Non-Callable [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | 3,097,084,000 |  |  |  | 2,086,347,000 |  |  |  | 3,097,084,000 | 2,086,347,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 3,004,000 |  |  |  | 5,240,000 |  |  |  | 3,004,000 | 5,240,000 |
Financial derivatives, at fair value | $ (4,326,000) |  |  |  | $ (5,990,000) |  |  |  | $ (4,326,000) | $ (5,990,000) |
Derivative, Average Fixed Interest Rate | 2.42% |  |  |  | 1.88% |  |  |  | 2.42% | 1.88% |
Derivative, Average Variable Interest Rate | 2.58% |  |  |  | 1.40% |  |  |  | 2.58% | 1.40% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 9 years 8 months 29 days | 5 years 5 months 17 days |
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest Rate Swap, Receive Fixed Non-Callable [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | $ 2,031,200,000 |  |  |  | $ 1,559,700,000 |  |  |  | $ 2,031,200,000 | $ 1,559,700,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 885,000 |  |  |  | 110,000 |  |  |  | 885,000 | 110,000 |
Financial derivatives, at fair value | $ (4,512,000) |  |  |  | $ (4,033,000) |  |  |  | $ (4,512,000) | $ (4,033,000) |
Derivative, Average Fixed Interest Rate | 2.49% |  |  |  | 1.38% |  |  |  | 2.49% | 1.38% |
Derivative, Average Variable Interest Rate | 1.94% |  |  |  | 1.45% |  |  |  | 1.94% | 1.45% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 1 year 8 months 5 days | 1 year 8 months 5 days |
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Rate Swap, Pay Fixed Non-Callable [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | $ 373,000,000 |  |  |  | $ 365,500,000 |  |  |  | $ 373,000,000 | $ 365,500,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 2,441,000 |  |  |  | 1,402,000 |  |  |  | 2,441,000 | 1,402,000 |
Financial derivatives, at fair value | $ (99,000) |  |  |  | $ (138,000) |  |  |  | $ (99,000) | $ (138,000) |
Derivative, Average Fixed Interest Rate | 2.40% |  |  |  | 2.16% |  |  |  | 2.40% | 2.16% |
Derivative, Average Variable Interest Rate | 2.83% |  |  |  | 1.74% |  |  |  | 2.83% | 1.74% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 6 years 1 month 12 days | 5 years 10 months 3 days |
Not Designated as Hedging Instrument [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Credit Risk Valuation Adjustment, Derivative Assets | $ 60,000 |  |  |  | $ 16,000 |  |  |  | $ 60,000 | $ 16,000 |
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities | 21,000 |  |  |  | 56,000 |  |  |  | 21,000 | 56,000 |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | (1,792,000) | 2,379,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total interest expense |  |  |  |  |  |  |  |  | (10,920,000) | (10,200,000) | (11,480,000)
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | (7,206,000) | (12,240,000) | (9,489,000)
Not Designated as Hedging Instrument [Member] | Interest Rate Swap, Pay Fixed Non-Callable [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | 316,664,000 |  |  |  | 345,333,000 |  |  |  | 316,664,000 | 345,333,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 796,000 |  |  |  | 339,000 |  |  |  | 796,000 | 339,000 |
Financial derivatives, at fair value | $ (10,399,000) |  |  |  | $ (16,352,000) |  |  |  | $ (10,399,000) | $ (16,352,000) |
Derivative, Average Fixed Interest Rate | 3.69% |  |  |  | 3.79% |  |  |  | 3.69% | 3.79% |
Derivative, Average Variable Interest Rate | 2.52% |  |  |  | 1.40% |  |  |  | 2.52% | 1.40% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 6 years 2 months 29 days | 6 years 8 months 5 days |
Not Designated as Hedging Instrument [Member] | Interest Rate Swap, Receive Fixed Non-Callable [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | $ 2,347,371,000 |  |  |  | $ 3,409,916,000 |  |  |  | $ 2,347,371,000 | $ 3,409,916,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 0 |  |  |  | 0 |  |  |  | 0 | 0 |
Financial derivatives, at fair value | $ 0 |  |  |  | $ 0 |  |  |  | $ 0 | $ 0 |
Derivative, Average Fixed Interest Rate | 2.10% |  |  |  | 1.24% |  |  |  | 2.10% | 1.24% |
Derivative, Average Variable Interest Rate | 2.37% |  |  |  | 1.25% |  |  |  | 2.37% | 1.25% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 10 months 10 days | 11 months |
Not Designated as Hedging Instrument [Member] | Basis Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | $ 1,770,026,000 |  |  |  | $ 1,053,500,000 |  |  |  | $ 1,770,026,000 | $ 1,053,500,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 421,000 |  |  |  | 18,000 |  |  |  | 421,000 | 18,000 |
Financial derivatives, at fair value | $ (130,000) |  |  |  | $ (106,000) |  |  |  | $ (130,000) | $ (106,000) |
Derivative, Average Variable Interest Rate | 2.45% |  |  |  | 1.33% |  |  |  | 2.45% | 1.33% |
Derivative, Variable Interest Rate | 2.49% |  |  |  | 1.42% |  |  |  | 2.49% | 1.42% |
Derivative, Average Remaining Maturity |  |  |  |  |  |  |  |  | 1 year 3 months 7 days | 10 months 28 days |
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | $ 588,000 | 226,000
Not Designated as Hedging Instrument [Member] | Future [Member] |  |  |  |  |  |  |  |  |  |  |
Notional Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative, Notional Amount | $ 20,400,000 |  |  |  | $ 40,000,000 |  |  |  | $ 20,400,000 | 40,000,000 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Financial derivatives, at fair value | 0 |  |  |  | 0 |  |  |  | 0 | 0 |
Financial derivatives, at fair value | $ (188,000) |  |  |  | $ (36,000) |  |  |  | $ (188,000) | $ (36,000) |
Derivative, Weighted-Average Forward Price |  |  |  |  |  |  |  |  | $ 121.09 | $ 123.96 |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | $ (27,000) | $ (340,000) | 162,000
Interest Income [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 |  |
Interest Income [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Fair Value Hedges Recognized in Earnings |  |  |  |  |  |  |  |  | 1,181,000 | 0 | 0
Interest Income [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Net Interest Settlements |  |  |  |  |  |  |  |  | 1,861,000 | (10,346,000) | (15,494,000)
Income_Expense related to interest settlements on fair value hedges |  |  |  |  |  |  |  |  | 67,099,000 | 36,043,000 | 19,675,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Income [Member] | Cash Flow Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments |  |  |  |  |  |  |  |  | 0 | 0 | 0
Interest Income [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Hedged Item Net Interest Settlements |  |  |  |  |  |  |  |  | 65,238,000 | 46,389,000 | 35,169,000
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Interest Income [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total interest expense |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Future [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Loans and Finance Receivables [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 |  |
Loans and Finance Receivables [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Fair Value Hedges Recognized in Earnings |  |  |  |  |  |  |  |  | (212,000) | 0 | 0
Loans and Finance Receivables [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Net Interest Settlements |  |  |  |  |  |  |  |  | (630,000) | (1,141,000) | (1,011,000)
Income_Expense related to interest settlements on fair value hedges |  |  |  |  |  |  |  |  | 5,654,000 | 2,238,000 | 1,052,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness |  |  |  |  |  |  |  |  |  | 0 | 0
Loans and Finance Receivables [Member] | Cash Flow Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments |  |  |  |  |  |  |  |  | 0 | 0 | 0
Loans and Finance Receivables [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Hedged Item Net Interest Settlements |  |  |  |  |  |  |  |  | 6,284,000 | 3,379,000 | 2,063,000
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total interest expense |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member] | Future [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Interest Expense [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 |  |
Interest Expense [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Fair Value Hedges Recognized in Earnings |  |  |  |  |  |  |  |  | 3,972,000 | 0 | 0
Interest Expense [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Net Interest Settlements |  |  |  |  |  |  |  |  | (7,995,000) | 2,642,000 | 132,000
Income_Expense related to interest settlements on fair value hedges |  |  |  |  |  |  |  |  | (45,500,000) | (11,986,000) | 132,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Expense [Member] | Cash Flow Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | (6,000) | (5,000) | (1,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax |  |  |  |  |  |  |  |  | 316,000 | (1,974,000) | (2,126,000)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item |  |  |  |  |  |  |  |  | (9,182,000) | (4,133,000) | (1,437,000)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments |  |  |  |  |  |  |  |  | (8,872,000) | (6,112,000) | (3,564,000)
Interest Expense [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Hedged Item Net Interest Settlements |  |  |  |  |  |  |  |  | (36,837,000) | (14,283,000) | 0
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | (668,000) | (345,000) | 0
Interest Expense [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Expense [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total interest expense |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Interest Expense [Member] | Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 0 | 0
Interest Expense [Member] | Not Designated as Hedging Instrument [Member] | Future [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Derivative Instruments [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | 3,687,000 | (1,792,000) | 2,379,000
Gain (Loss) on Derivative Instruments [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Derivative Net Interest Settlements |  |  |  |  |  |  |  |  | 0 | 0 | 0
Income_Expense related to interest settlements on fair value hedges |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Fair Value Hedges Recognized in Earnings |  |  |  |  |  |  |  |  | 0 | (719,000) | 5,043,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness |  |  |  |  |  |  |  |  |  | (320,000) | (353,000)
Gain (Loss) on Derivative Instruments [Member] | Cash Flow Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax |  |  |  |  |  |  |  |  | 0 | 0 | 0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments |  |  |  |  |  |  |  |  | 0 | (320,000) | (353,000)
Gain (Loss) on Derivative Instruments [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Hedged Item Net Interest Settlements |  |  |  |  |  |  |  |  | 0 | 0 | 0
Premium_Discount recognized on hedged item |  |  |  |  |  |  |  |  | 0 | 0 | 0
Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total interest expense |  |  |  |  |  |  |  |  | (10,920,000) | (10,200,000) | (11,480,000)
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | (7,206,000) | (12,240,000) | (9,489,000)
Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  |  | 588,000 | 226,000
Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member] | Future [Member] |  |  |  |  |  |  |  |  |  |  |
Derivative, Collateral [Abstract] |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  |  |  |  |  |  |  | $ (27,000) | $ (340,000) | $ 162,000

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