Derivative Instruments and Hedging Activities Schedule of Inverse Interest-Only Securities Reconciliation (Details) - USD ($) |
Sep. 30, 2018 |
Jun. 30, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Dec. 31, 2016 |
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| Derivatives, Fair Value [Line Items] | ||||||
| Accrued interest receivable | $ 85,257,000 | $ 68,309,000 | ||||
| Face Value | 41,330,283,000 | $ 28,618,861,000 | 31,226,878,000 | $ 24,113,321,000 | $ 16,988,116,000 | $ 18,802,500,000 |
| Derivative Financial Instruments, Assets [Member] | ||||||
| Derivatives, Fair Value [Line Items] | ||||||
| Fair Value | 403,231,000 | 309,918,000 | ||||
| Face Value | 33,229,283,000 | 25,503,371,000 | ||||
| Inverse Interest-Only Securities [Member] | ||||||
| Derivatives, Fair Value [Line Items] | ||||||
| Fair Value | 67,665,000 | 91,827,000 | ||||
| Accrued interest receivable | 600,000 | 900,000 | ||||
| Face Value | 498,826,000 | 588,246,000 | ||||
| Amortized Cost | 73,098,000 | 86,734,000 | ||||
| Gross unrealized gains | 2,668,000 | 6,843,000 | ||||
| Gross unrealized losses | (8,726,000) | (2,602,000) | ||||
| Market Value | 67,040,000 | 90,975,000 | ||||
| Inverse Interest-Only Securities [Member] | Derivative Financial Instruments, Assets [Member] | ||||||
| Derivatives, Fair Value [Line Items] | ||||||
| Face Value | $ 498,826,000 | $ 588,246,000 |
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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the cost of inverse interest-only residential mortgage securities (Agency derivatives), net of adjustments including accretion, amortization, and fair value hedge accounting adjustments, if any. No definition available.
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- Definition Carrying value (excluding accrued interest receivable) as of the balance sheet date of the assets less the liabilities of a derivative or group of derivatives. No definition available.
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- Definition This item represents the gross unrealized gains for inverse interest-only residential mortgage securities (Agency derivatives), at a point in time. No definition available.
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- Definition This item represents the gross unrealized losses for inverse interest-only residential mortgage securities (Agency derivatives), at a point in time. No definition available.
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- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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