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Derivatives Volume of Activity (Details) | 3 Months Ended
--- | ---
Mar. 31, 2020 USD ($)
Derivative [Line Items] |  |
Derivative Liability, Notional Amount | $ 1,177,500,000 |
Not Designated as Hedging Instrument, Economic Hedge | Interest rate swaps |  |
Derivative [Line Items] |  |
Derivative Asset, Notional Amount | 4,225,000,000 |
Notional Amount of Derivative Instruments Added | (2,570,000,000) |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (6,565,000,000) |
Derivative Asset, Notional Amount | 230,000,000 |
Not Designated as Hedging Instrument, Economic Hedge | Interest rate swaption |  |
Derivative [Line Items] |  |
Derivative Asset, Notional Amount | 750,000,000 | [1]
Notional Amount of Derivative Instruments Added | 0 |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (750,000,000) |
Derivative Asset, Notional Amount | 0 |
Not Designated as Hedging Instrument, Economic Hedge | U.S. Treasury futures |  |
Derivative [Line Items] |  |
Derivative Liability, Notional Amount | 0 |
Notional Amount of Derivative Instruments Added | (1,477,500,000) |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (300,000,000) |
Derivative Liability, Notional Amount | 1,177,500,000 |
Not Designated as Hedging Instrument, Economic Hedge | Options on U.S. Treasury futures |  |
Derivative [Line Items] |  |
Derivative Asset, Notional Amount | 1,350,000,000 | [1]
Notional Amount of Derivative Instruments Added | (2,000,000,000) |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (1,650,000,000) |
Derivative Asset, Notional Amount | 1,700,000,000 | [2]
Not Designated as Hedging Instrument, Economic Hedge | TBA securities | Short position |  |
Derivative [Line Items] |  |
Derivative Liability, Notional Amount | 500,000,000 |
Notional Amount of Derivative Instruments Added | (830,000,000) |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (815,000,000) |
Derivative Liability, Notional Amount | 515,000,000 |
Not Designated as Hedging Instrument, Trading | TBA securities | Long position |  |
Derivative [Line Items] |  |
Derivative Asset, Notional Amount | 435,000,000 |
Notional Amount of Derivative Instruments Added | (1,905,000,000) |
Notional Amount of Derivative Instruments Maturing, Settled, Terminated, or Paired-Off | (2,340,000,000) |
Derivative Asset, Notional Amount | $ 0 |
[1] | All options outstanding as of December 31, 2019 expired during the first quarter of 2020.
[2] | All futures and options outstanding as of March 31, 2020 will expire in June of 2020

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