Consolidations and Transfers of Financial Assets (Policies)	12 Months Ended
Dec. 31, 2019
Consolidations and Transfers of Financial Assets [Abstract]
Principles of Consolidation Policy	Principles of Consolidation Our consolidated financial statements include our accounts as well as the accounts of the other entities in which we have a controlling financial interest. All intercompany balances and transactions have been eliminated. The typical condition for a controlling financial interest is ownership of a majority of the voting interests of an entity. A controlling financial interest may also exist in an entity such as a variable interest entity (“VIE”) through arrangements that do not involve voting interests Consolidated VIEs If an entity is a VIE, we consider whether our variable interest in that entity causes us to be the primary beneficiary. The primary beneficiary of the VIE is required to consolidate and account for the assets, liabilities and noncontrolling interests of the VIE in its consolidated financial statements. An enterprise is deemed to be the primary beneficiary when the enterprise has the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and exposure to benefits and/or losses could potentially be significant to the entity. In general, the investors in the obligations of consolidated VIEs have recourse only to the assets of those VIEs and do not have recourse to us, except where we provide a guaranty to the VIE. We continually assess whether we are the primary beneficiary of the VIEs with which we are involved and therefore may consolidate or deconsolidate a VIE through the duration of our involvement. Unconsolidated VIEs We do not consolidate VIEs when we are not deemed to be the primary beneficiary.
Transfers and Servicing of Financial Assets Policy	Transfers of Financial Assets We evaluate each transfer of financial assets to determine whether the transfer qualifies as a sale. If a transfer does not meet the criteria for sale treatment, the transferred assets remain in our consolidated balance sheets and we record a liability to the extent of any proceeds received in connection with the transfer. We record transfers of financial assets in which we surrender control of the transferred assets as sales. When a transfer that qualifies as a sale is completed, we derecognize all assets transferred and recognize all assets obtained and liabilities incurred at fair value. The difference between the carrying basis of the assets transferred and the fair value of the net proceeds from the sale is recorded as a component of “Investment gains, net” in our consolidated statements of operations and comprehensive income. Retained interests are primarily derived from transfers associated with our portfolio securitizations in the form of Fannie Mae securities. We separately describe the subsequent accounting, as well as how we determine fair value, for our retained interests in the “Investments in Securities” section of this note. We enter into repurchase agreements that involve contemporaneous trades to purchase and sell securities. These transactions are accounted for as secured financings since the transferor has not relinquished control over the transferred assets. These transactions are reported as securities purchased under agreements to resell and securities sold under agreements to repurchase in our consolidated balance sheets except for securities purchased under agreements to resell on an overnight basis, which are included in cash and cash equivalents in our consolidated balance sheets. The substantial majority of these portfolio securitization transactions generally do not qualify for sale treatment. Portfolio securitization trusts that do qualify for sale treatment primarily consist of loans that are guaranteed or insured, in whole or in part, by the U.S. government.We retain interests from the transfer and sale of mortgage-related securities to unconsolidated single-class and multi-class portfolio securitization trusts.We issue Fannie Mae MBS through portfolio securitization transactions by transferring pools of mortgage loans or mortgage-related securities to one or more trusts or special purpose entities. We are considered to be the transferor when we transfer assets from our own retained mortgage portfolio in a portfolio securitization transaction.

Consolidations and Transfers of Financial Assets (Policies)

12 Months Ended

Dec. 31, 2019

Consolidations and Transfers of Financial Assets [Abstract]

Principles of Consolidation

Our consolidated financial statements include our accounts as well as the accounts of the other entities in which we have a controlling financial interest. All intercompany balances and transactions have been eliminated. The typical condition for a controlling financial interest is ownership of a majority of the voting interests of an entity. A controlling financial interest may also exist in an entity such as a variable interest entity (“VIE”) through arrangements that do not involve voting interests

Consolidated VIEs

If an entity is a VIE, we consider whether our variable interest in that entity causes us to be the primary beneficiary. The primary beneficiary of the VIE is required to consolidate and account for the assets, liabilities and noncontrolling interests of the VIE in its consolidated financial statements. An enterprise is deemed to be the primary beneficiary when the enterprise has the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and exposure to benefits and/or losses could potentially be significant to the entity. In general, the investors in the obligations of consolidated VIEs have recourse only to the assets of those VIEs and do not have recourse to us, except where we provide a guaranty to the VIE.

We continually assess whether we are the primary beneficiary of the VIEs with which we are involved and therefore may consolidate or deconsolidate a VIE through the duration of our involvement.

Unconsolidated VIEs

We do not consolidate VIEs when we are not deemed to be the primary beneficiary.

Transfers and Servicing of Financial Assets Policy

Transfers of Financial Assets

We evaluate each transfer of financial assets to determine whether the transfer qualifies as a sale. If a transfer does not meet the criteria for sale treatment, the transferred assets remain in our consolidated balance sheets and we record a liability to the extent of any proceeds received in connection with the transfer. We record transfers of financial assets in which we surrender control of the transferred assets as sales.

When a transfer that qualifies as a sale is completed, we derecognize all assets transferred and recognize all assets obtained and liabilities incurred at fair value. The difference between the carrying basis of the assets transferred and the fair value of the net proceeds from the sale is recorded as a component of “Investment gains, net” in our consolidated statements of operations and comprehensive income. Retained interests are primarily derived from transfers associated with our portfolio securitizations in the form of Fannie Mae securities. We separately describe the subsequent accounting, as well as how we determine fair value, for our retained interests in the “Investments in Securities” section of this note.

We enter into repurchase agreements that involve contemporaneous trades to purchase and sell securities. These transactions are accounted for as secured financings since the transferor has not relinquished control over the transferred assets. These transactions are reported as securities purchased under agreements to resell and securities sold under agreements to repurchase in our consolidated balance sheets except for securities purchased under agreements to resell on an overnight basis, which are included in cash and cash equivalents in our consolidated balance sheets.

The substantial majority of these portfolio securitization transactions generally do not qualify for sale treatment. Portfolio securitization trusts that do qualify for sale treatment primarily consist of loans that are guaranteed or insured, in whole or in part, by the U.S. government.We retain interests from the transfer and sale of mortgage-related securities to unconsolidated single-class and multi-class portfolio securitization trusts.We issue Fannie Mae MBS through portfolio securitization transactions by transferring pools of mortgage loans or mortgage-related securities to one or more trusts or special purpose entities. We are considered to be the transferor when we transfer assets from our own retained mortgage portfolio in a portfolio securitization transaction.