Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2020
Credit Loss, Financial Instrument [Policy Text Block]	Beginning January 1, 2020, the Bank adopted new accounting guidance pertaining to the measurement of credit losses on financial instruments that requires a financial asset or group of financial assets measured at amortized cost to be presented at the net amount expected to be collected. The new guidance also requires credit losses relating to these financial instruments as well as AFS to be recorded through the allowance for credit losses (ACL). Key changes as compared to prior accounting guidance are detailed below. Consistent with the modified retrospective method of adoption, the prior period has not been revised to conform to the new basis of accounting. For information on the prior accounting treatment, see Note 1 - Summary of Significant Accounting Policies of the audited financial statements in the Bank’s 2019 Form 10-K. Interest-Bearing Deposits, Securities Purchased under Agreements to Resell, and Federal Funds Sold. The Bank invests in interest-bearing deposits, securities purchased under agreements to resell, and Federal funds sold. These investments provide short-term liquidity and are carried at amortized cost. Accrued interest receivable is recorded separately on the Statement of Condition. These investments are evaluated quarterly for expected credit losses. If applicable, an ACL is recorded with a corresponding adjustment to the provision for credit losses. The Bank uses the collateral maintenance provision practical expedient for securities purchased under agreements to resell. Consequently, a credit loss would be recognized if there is a collateral shortfall which the Bank does not believe the counterparty will replenish in accordance with its contractual terms. The credit loss would be limited to the difference between the fair value of the collateral and the investment’s amortized cost. See Note 2 - Investments for details on the allowance methodologies relating to these investments. Investment Securities. AFS. AFS securities are evaluated quarterly for expected credit losses on an individual security basis. In assessing whether a credit loss exists, the Bank considers whether there would be a shortfall in receiving all cash flows contractually due. If a shortfall is projected to occur, the Bank recognizes an ACL. The ACL is limited to the amount of the AFS security’s unrealized loss, if any. If the AFS security is in an unrealized gain position, the ACL is zero. The ACL excludes uncollectible accrued interest receivable, which is measured separately. Prior to January 1, 2020, credit losses were recorded as a direct write–down of the AFS security's amortized cost. If the Bank intends to sell an AFS security in an unrealized loss position, or more likely than not will be required to sell the security, any ACL is written off and the amortized cost basis is written down to the security’s fair value with any incremental impairment reported in earnings as net gains (losses) on investment securities. For AFS securities with OTTI recognized prior to January 1, 2020, the accretable yield continues to be used prospectively. Based on the quarterly assessment of expected credit losses, if there is an improvement, the Bank will first recognize a benefit for credit losses up to the amount of the ACL. If the ACL is zero and the increase in cash flows is significant, the Bank will adjust the accretable yield prospectively. Effective January 1, 2020, the net non-credit portion of OTTI gains (losses) on AFS securities was reclassified to net unrealized gains (losses) on AFS securities within OCI. HTM. Securities that the Bank has both the ability and intent to hold to maturity are classified as HTM and are carried at amortized cost, which is cost net of periodic principal repayments and amortization of premiums and accretion of discounts. Accrued interest receivable is recorded separately on the Statement of Condition. HTM securities are evaluated quarterly for expected credit losses on a pool basis unless an individual assessment is deemed necessary because the securities do not possess similar risk characteristics. An ACL is recorded with a corresponding adjustment to the provision for credit losses. The ACL excludes uncollectible accrued interest receivable, which is measured separately. See Note 2 - Investments for details on the allowance methodologies relating to AFS and HTM securities. Advances. Advances are carried at amortized cost, which is cost net of periodic principal repayments, net of amortization of premiums and discounts (including discounts related to AHP) and hedging adjustments. Accrued interest receivable is recorded separately on the Combined Statement of Condition. Advances are evaluated quarterly for expected credit losses. If deemed necessary, an ACL is recorded with a corresponding adjustment to the provision for credit losses. See Note 3 - Advances for details on the allowance methodology relating to advances. Mortgage Loans Held for Portfolio. Mortgage loans held for portfolio are recorded at amortized cost, which is cost, net of periodic principal repayments and amortization of premiums and accretion of discounts, hedging adjustments, and direct write-downs. Accrued interest receivable is recorded separately on the Statement of Condition. The Bank performs a quarterly assessment of its mortgage loans held for portfolio to estimate expected credit losses. An ACL is recorded with a corresponding adjustment to the provision for credit losses The Bank measures expected credit losses on mortgage loans on a collective basis, pooling loans with similar risk characteristics. If a mortgage loan no longer shares risk characteristics with other loans, it is removed from the pool and evaluated for expected credit losses on an individual basis. When developing the ACL, the Bank measures the estimated loss over the life of a mortgage loan and incorporates the credit enhancements of the MPF Program. If a loan is purchased at a discount, the discount does not offset the ACL. The Bank includes estimates of expected recoveries within the ACL. The allowance excludes uncollectible accrued interest receivable, as the Bank writes-off accrued interest receivable by reversing interest income if a mortgage loan is placed on nonaccrual status. The Bank does not purchase mortgage loans with credit deterioration present at the time of purchase. See Note 4 - Mortgage Loans for details on the allowance methodologies relating to mortgage loans. Off-Balance Sheet Credit Exposures. The Bank evaluates its off-balance sheet credit exposures on a quarterly basis for expected credit losses. If deemed necessary, an allowance for expected credit losses is recorded in other liabilities with a corresponding adjustment to the provision for credit losses. Commitments to purchase MPF Loans are derivatives and therefore do not require an assessment of expected credit losses. Troubled Debt Restructuring Relief On March 27, 2020, the Coronavirus, Aid, Relief, and Economic Security Act (the CARES Act) providing optional, temporary relief from accounting for certain loan modifications as troubled debt restructurings (TDRs) was signed into law. Under the CARES Act, TDR relief is available to banks for loan modifications related to the adverse effects of COVID-19 (COVID-related modifications) granted to borrowers that are current as of December 31, 2019. TDR relief applies to COVID- related modifications made from March 1, 2020, until the earlier of December 31, 2020, or 60 days following the termination of the national emergency declared by the President of the United States. Beginning in second quarter 2020, the Bank elected to apply the TDR relief provided by the CARES Act.
Derivatives, Policy	The Bank is subject to credit risk due to the risk of nonperformance by counterparties to its derivative transactions. The Bank manages counterparty credit risk through credit analysis, collateral requirements, and adherence to the requirements set forth in its policies, U.S. Commodity Futures Trading Commission regulations, and Finance Agency regulations.Uncleared Derivatives. For uncleared derivatives, the degree of credit risk depends on the extent to which netting arrangements are included in such contracts to mitigate the risk. The Bank requires collateral agreements with collateral delivery thresholds on all uncleared derivatives.Generally, the Bank is subject to certain ISDA agreements for uncleared derivatives that require the Bank to post additional collateral with its counterparties if there is deterioration in the Bank's credit rating and the net liability position exceeds the relevant threshold. If the Bank’s credit rating were to be lowered by a major credit rating agency, the Bank would be required to deliver additional collateral on uncleared derivative instruments in net liability positions, unless the collateral delivery threshold is set to zero.
Fair Value Measurement, Policy	Fair Value Hierarchy. The fair value hierarchy is used to prioritize the inputs used to measure fair value by maximizing the use of observable inputs. The inputs are evaluated and an overall level for the fair value measurement is determined. This overall level is an indication of the market observability of the fair value measurement for the asset or liability. The fair value hierarchy prioritizes the inputs used to measure fair value into three broad levels: Level 1 Inputs - Quoted prices (unadjusted) for identical assets or liabilities in an active market that the reporting entity can access on the measurement date. An active market for the asset or liability is a market in which the transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 Inputs - Inputs other than quoted prices within Level 1 that are observable inputs for the asset or liability, either directly or indirectly. If the asset or liability has a specified (contractual) term, a Level 2 input must be observable for substantially the full term of the asset or liability. Level 2 inputs include the following: (1) quoted prices for similar assets or liabilities in active markets; (2) quoted prices for identical or similar assets or liabilities in markets that are not active or in which little information is released publicly; (3) inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates and yield curves that are observable at commonly quoted intervals, and implied volatilities) and (4) inputs that are derived principally from or corroborated by observable market data by correlation or other means. Level 3 Inputs - Unobservable inputs for the asset or liability. The Bank reviews its fair value hierarchy classifications on a quarterly basis. Changes in the observability of the valuation inputs may result in a reclassification of certain assets or liabilities. These reclassifications are reported as transfers in/out as of the beginning of the quarter in which the changes occur.
Fair Value of Financial Instruments, Policy	Investment Securities – MBS. To value MBS holdings, the Bank obtains prices from multiple third-party pricing vendors, when available. The pricing vendors use various proprietary models to price MBS. The inputs to those models are derived from various sources including, but not limited to: benchmark yields, reported trades, dealer estimates, issuer spreads, benchmark securities, bids, offers and other market-related data. Since many MBS do not trade on a daily basis, the pricing vendors use available information such as benchmark curves, benchmarking of like securities, sector groupings and matrix pricing to determine the prices for individual securities, as applicable. Each pricing vendor has an established challenge process in place for all MBS valuations, which facilitates resolution of potentially erroneous prices identified by the Bank. The Bank's valuation technique first requires the establishment of a median price for each security. All prices that are within a specified tolerance threshold of the median price are included in the cluster of prices that are averaged to compute a default price. Prices that are outside the threshold (outliers) are subject to further analysis (including, but not limited to, comparison to prices provided by an additional third-party valuation service, prices for similar securities, and/or non-binding dealer estimates) to determine if an outlier is a better estimate of fair value. If an outlier (or some other price identified in the analysis) is determined to be a better estimate of fair value, then the outlier (or the other price as appropriate) is used as the price rather than the default price. If, on the other hand, the analysis confirms that an outlier (or outliers) is (are) in fact not representative of fair value and the default price is the best estimate, then the default price is used as the final price. In all cases, the final price is used to determine the fair value of the security. If all prices received for a security are outside the tolerance threshold level of the median price, then there is no default price, and the final price is determined by an evaluation of all outlier prices as described above.Derivative Assets/Liabilities. The Bank bases the fair values of derivatives with similar terms on market prices, when available. However, market prices do not exist for many types of derivative instruments. Consequently, fair values for these instruments are estimated using standard valuation techniques such as discounted cash flow analysis and comparisons to similar instruments. Estimates developed using these methods are highly subjective and require judgment regarding significant matters such as the amount and timing of future cash flows, volatility of interest rates and the selection of discount rates that appropriately reflect market and credit risks. In addition, the fair value estimates for these instruments include accrued interest receivable/payable which approximate their carrying values due to their short-term nature. The discounted cash flow analysis used to determine the net present value of derivative instruments utilizes market-observable inputs (inputs that are actively quoted and can be validated to external sources). Inputs by class of derivative are as follows: Interest-rate related: •Discount rate assumption. SOFR curve for SOFR indexed swaps. Overnight Index Swap (OIS) curve for all other swaps. •Forward interest rate assumption (rates projected in order to calculate cash flows through the designated term of the hedge relationship). LIBOR Swap curve, OIS curve or SOFR curve. •Volatility assumption. Market-based expectations of future interest rate volatility implied from current market prices for similar options. Mortgage delivery commitments: •TBA securities prices. Market-based prices of TBAs are determined by coupon class and expected term until settlement and a pricing adjustment reflective of the secondary mortgage market. The Bank is subject to credit risk on uncleared derivatives transactions due to the potential nonperformance by the derivatives counterparties. To mitigate this risk, the Bank has entered into netting arrangements and security agreements that provide for delivery of collateral at specified levels. As a result, uncleared derivatives are recognized as collateralized-to-market and the fair value of uncleared derivatives excludes netting adjustments and collateral. The Bank has evaluated the potential for fair value adjustment due to uncleared counterparty credit risk and has concluded that no adjustments are necessary. The Bank's credit risk exposure on cleared derivatives is mitigated through the delivery of initial margin to offset future changes in value and daily delivery of variation margin to offset changes in market value. This is executed through the use of a central counterparty, CME. Variation margin payments are daily settlement payments rather than collateral. Initial margin continues to be treated as collateral and accounted for separately. The fair values of derivatives are netted by clearing agent and/or by counterparty pursuant to the provisions of each of the Bank’s netting agreements. If these netted amounts are positive, they are classified as an asset and, if negative, as a liability. Impaired Mortgage Loans Held for Portfolio and REO. The estimated fair values of impaired mortgage loans held for portfolio and real estate owned are determined based on values provided by a third party's retail-based AVM. The Bank adjusts the AVM value based on the amount it has historically received on liquidation. Subjectivity of Estimates. Estimates of the fair value of financial assets and liabilities using the methods described above are highly subjective and require judgments regarding significant matters such as the amount and timing of future cash flows, prepayment speed assumptions, expected interest rate volatility, possible distributions of future interest rates used to value options, and the selection of discount rates that appropriately reflect market and credit risks. The use of different assumptions could have a material effect on the fair value estimates. These estimates are susceptible to material near term changes because they are made as of a specific point in time.
Fair Value Transfer, Policy	For instruments carried at fair value, the Bank reviews the fair value hierarchy classifications each quarter. Changes in the observability of the valuation attributes may result in a reclassification of certain financial assets or liabilities. Such reclassifications are reported as transfers in/out at fair value in the quarter in which the changes occur. Transfers are reported as of the beginning of the period.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2020

Credit Loss, Financial Instrument [Policy Text Block]

Beginning January 1, 2020, the Bank adopted new accounting guidance pertaining to the measurement of credit losses on financial instruments that requires a financial asset or group of financial assets measured at amortized cost to be presented at the net amount expected to be collected. The new guidance also requires credit losses relating to these financial instruments as well as AFS to be recorded through the allowance for credit losses (ACL). Key changes as compared to prior accounting guidance are detailed below. Consistent with the modified retrospective method of adoption, the prior period has not been revised to conform to the new basis of accounting. For information on the prior accounting treatment, see Note 1 - Summary of Significant Accounting Policies of the audited financial statements in the Bank’s 2019 Form 10-K.

Interest-Bearing Deposits, Securities Purchased under Agreements to Resell, and Federal Funds Sold. The Bank invests in interest-bearing deposits, securities purchased under agreements to resell, and Federal funds sold. These investments provide short-term liquidity and are carried at amortized cost. Accrued interest receivable is recorded separately on the Statement of Condition.

These investments are evaluated quarterly for expected credit losses. If applicable, an ACL is recorded with a corresponding adjustment to the provision for credit losses. The Bank uses the collateral maintenance provision practical expedient for securities purchased under agreements to resell. Consequently, a credit loss would be recognized if there is a collateral shortfall which the Bank does not believe the counterparty will replenish in accordance with its contractual terms. The credit loss would be limited to the difference between the fair value of the collateral and the investment’s amortized cost.

See Note 2 - Investments for details on the allowance methodologies relating to these investments.

Investment Securities.

AFS. AFS securities are evaluated quarterly for expected credit losses on an individual security basis. In assessing whether a credit loss exists, the Bank considers whether there would be a shortfall in receiving all cash flows contractually due. If a shortfall is projected to occur, the Bank recognizes an ACL. The ACL is limited to the amount of the AFS security’s unrealized loss, if any. If the AFS security is in an unrealized gain position, the ACL is zero. The ACL excludes uncollectible accrued interest receivable, which is measured separately. Prior to January 1, 2020, credit losses were recorded as a direct write–down of the AFS security's amortized cost.

If the Bank intends to sell an AFS security in an unrealized loss position, or more likely than not will be required to sell the security, any ACL is written off and the amortized cost basis is written down to the security’s fair value with any incremental impairment reported in earnings as net gains (losses) on investment securities.

For AFS securities with OTTI recognized prior to January 1, 2020, the accretable yield continues to be used prospectively. Based on the quarterly assessment of expected credit losses, if there is an improvement, the Bank will first recognize a benefit for credit losses up to the amount of the ACL. If the ACL is zero and the increase in cash flows is significant, the Bank will adjust the accretable yield prospectively.

Effective January 1, 2020, the net non-credit portion of OTTI gains (losses) on AFS securities was reclassified to net unrealized gains (losses) on AFS securities within OCI.

HTM. Securities that the Bank has both the ability and intent to hold to maturity are classified as HTM and are carried at amortized cost, which is cost net of periodic principal repayments and amortization of premiums and accretion of discounts. Accrued interest receivable is recorded separately on the Statement of Condition.

HTM securities are evaluated quarterly for expected credit losses on a pool basis unless an individual assessment is deemed necessary because the securities do not possess similar risk characteristics. An ACL is recorded with a corresponding adjustment to the provision for credit losses. The ACL excludes uncollectible accrued interest receivable, which is measured separately.

See Note 2 - Investments for details on the allowance methodologies relating to AFS and HTM securities.

Advances. Advances are carried at amortized cost, which is cost net of periodic principal repayments, net of amortization of premiums and discounts (including discounts related to AHP) and hedging adjustments. Accrued interest receivable is recorded separately on the Combined Statement of Condition. Advances are evaluated quarterly for expected credit losses. If deemed necessary, an ACL is recorded with a corresponding adjustment to the provision for credit losses. See Note 3 - Advances for details on the allowance methodology relating to advances.

Mortgage Loans Held for Portfolio. Mortgage loans held for portfolio are recorded at amortized cost, which is cost, net of periodic principal repayments and amortization of premiums and accretion of discounts, hedging adjustments, and direct write-downs. Accrued interest receivable is recorded separately on the Statement of Condition. The Bank performs a quarterly assessment of its mortgage loans held for portfolio to estimate expected credit losses. An ACL is recorded with a corresponding adjustment to the provision for credit losses

The Bank measures expected credit losses on mortgage loans on a collective basis, pooling loans with similar risk characteristics. If a mortgage loan no longer shares risk characteristics with other loans, it is removed from the pool and evaluated for expected credit losses on an individual basis.

When developing the ACL, the Bank measures the estimated loss over the life of a mortgage loan and incorporates the credit enhancements of the MPF Program. If a loan is purchased at a discount, the discount does not offset the ACL. The Bank includes estimates of expected recoveries within the ACL. The allowance excludes uncollectible accrued interest receivable, as the Bank writes-off accrued interest receivable by reversing interest income if a mortgage loan is placed on nonaccrual status.

The Bank does not purchase mortgage loans with credit deterioration present at the time of purchase. See Note 4 - Mortgage Loans for details on the allowance methodologies relating to mortgage loans.

Off-Balance Sheet Credit Exposures. The Bank evaluates its off-balance sheet credit exposures on a quarterly basis for expected credit losses. If deemed necessary, an allowance for expected credit losses is recorded in other liabilities with a corresponding adjustment to the provision for credit losses. Commitments to purchase MPF Loans are derivatives and therefore do not require an assessment of expected credit losses.

Troubled Debt Restructuring Relief

On March 27, 2020, the Coronavirus, Aid, Relief, and Economic Security Act (the CARES Act) providing optional, temporary relief from accounting for certain loan modifications as troubled debt restructurings (TDRs) was signed into law. Under the CARES Act, TDR relief is available to banks for loan modifications related to the adverse effects of COVID-19 (COVID-related modifications) granted to borrowers that are current as of December 31, 2019. TDR relief applies to COVID-

related modifications made from March 1, 2020, until the earlier of December 31, 2020, or 60 days following the termination of the national emergency declared by the President of the United States. Beginning in second quarter 2020, the Bank elected to apply the TDR relief provided by the CARES Act.

Derivatives, Policy

The Bank is subject to credit risk due to the risk of nonperformance by counterparties to its derivative transactions. The Bank manages counterparty credit risk through credit analysis, collateral requirements, and adherence to the requirements set forth in its policies, U.S. Commodity Futures Trading Commission regulations, and Finance Agency regulations.Uncleared Derivatives. For uncleared derivatives, the degree of credit risk depends on the extent to which netting arrangements are included in such contracts to mitigate the risk. The Bank requires collateral agreements with collateral delivery thresholds on all uncleared derivatives.Generally, the Bank is subject to certain ISDA agreements for uncleared derivatives that require the Bank to post additional collateral with its counterparties if there is deterioration in the Bank's credit rating and the net liability position exceeds the relevant threshold. If the Bank’s credit rating were to be lowered by a major credit rating agency, the Bank would be required to deliver additional collateral on uncleared derivative instruments in net liability positions, unless the collateral delivery threshold is set to zero.

Fair Value Measurement, Policy

Fair Value Hierarchy. The fair value hierarchy is used to prioritize the inputs used to measure fair value by maximizing the use of observable inputs. The inputs are evaluated and an overall level for the fair value measurement is determined. This overall level is an indication of the market observability of the fair value measurement for the asset or liability.

The fair value hierarchy prioritizes the inputs used to measure fair value into three broad levels:

Level 1 Inputs - Quoted prices (unadjusted) for identical assets or liabilities in an active market that the reporting entity can access on the measurement date. An active market for the asset or liability is a market in which the transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2 Inputs - Inputs other than quoted prices within Level 1 that are observable inputs for the asset or liability, either directly or indirectly. If the asset or liability has a specified (contractual) term, a Level 2 input must be observable for substantially the full term of the asset or liability. Level 2 inputs include the following: (1) quoted prices for similar assets or liabilities in active markets; (2) quoted prices for identical or similar assets or liabilities in markets that are not active or in which little information is released publicly; (3) inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates and yield curves that are observable at commonly quoted intervals, and implied volatilities) and (4) inputs that are derived principally from or corroborated by observable market data by correlation or other means.

Level 3 Inputs - Unobservable inputs for the asset or liability.

The Bank reviews its fair value hierarchy classifications on a quarterly basis. Changes in the observability of the valuation inputs may result in a reclassification of certain assets or liabilities. These reclassifications are reported as transfers in/out as of the beginning of the quarter in which the changes occur.

Fair Value of Financial Instruments, Policy

Investment Securities – MBS. To value MBS holdings, the Bank obtains prices from multiple third-party pricing vendors, when available. The pricing vendors use various proprietary models to price MBS. The inputs to those models are derived from various sources including, but not limited to: benchmark yields, reported trades, dealer estimates, issuer spreads, benchmark securities, bids, offers and other market-related data. Since many MBS do not trade on a daily basis, the pricing vendors use available information such as benchmark curves, benchmarking of like securities, sector groupings and matrix pricing to determine the prices for individual securities, as applicable. Each pricing vendor has an established challenge process in place for all MBS valuations, which facilitates resolution of potentially erroneous prices identified by the Bank. The Bank's valuation technique first requires the establishment of a median price for each security. All prices that are within a specified tolerance threshold of the median price are included in the cluster of prices that are averaged to compute a default price. Prices that are outside the threshold (outliers) are subject to further analysis (including, but not limited to, comparison to prices provided by an additional third-party valuation service, prices for similar securities, and/or non-binding dealer estimates) to determine if an outlier is a better estimate of fair value. If an outlier (or some other price identified in the analysis) is determined to be a better estimate of fair value, then the outlier (or the other price as appropriate) is used as the price rather than the default price. If, on the other hand, the analysis confirms that an outlier (or outliers) is (are) in fact not representative of fair value and the default price is the best estimate, then the default price is used as the final price. In all cases, the final price is used to determine the fair value of the security. If all prices received for a security are outside the tolerance threshold level of the median price, then there is no default price, and the final price is determined by an evaluation of all outlier prices as described above.Derivative Assets/Liabilities. The Bank bases the fair values of derivatives with similar terms on market prices, when available. However, market prices do not exist for many types of derivative instruments. Consequently, fair values for these

instruments are estimated using standard valuation techniques such as discounted cash flow analysis and comparisons to similar instruments. Estimates developed using these methods are highly subjective and require judgment regarding significant matters such as the amount and timing of future cash flows, volatility of interest rates and the selection of discount rates that appropriately reflect market and credit risks. In addition, the fair value estimates for these instruments include accrued interest receivable/payable which approximate their carrying values due to their short-term nature.

The discounted cash flow analysis used to determine the net present value of derivative instruments utilizes market-observable inputs (inputs that are actively quoted and can be validated to external sources). Inputs by class of derivative are as follows:

Interest-rate related:

•Discount rate assumption. SOFR curve for SOFR indexed swaps. Overnight Index Swap (OIS) curve for all other swaps.

•Forward interest rate assumption (rates projected in order to calculate cash flows through the designated term of the hedge relationship). LIBOR Swap curve, OIS curve or SOFR curve.

•Volatility assumption. Market-based expectations of future interest rate volatility implied from current market prices for similar options.

Mortgage delivery commitments:

•TBA securities prices. Market-based prices of TBAs are determined by coupon class and expected term until settlement and a pricing adjustment reflective of the secondary mortgage market.

The Bank is subject to credit risk on uncleared derivatives transactions due to the potential nonperformance by the derivatives counterparties. To mitigate this risk, the Bank has entered into netting arrangements and security agreements that provide for delivery of collateral at specified levels. As a result, uncleared derivatives are recognized as collateralized-to-market and the fair value of uncleared derivatives excludes netting adjustments and collateral. The Bank has evaluated the potential for fair value adjustment due to uncleared counterparty credit risk and has concluded that no adjustments are necessary.

The Bank's credit risk exposure on cleared derivatives is mitigated through the delivery of initial margin to offset future changes in value and daily delivery of variation margin to offset changes in market value. This is executed through the use of a central counterparty, CME. Variation margin payments are daily settlement payments rather than collateral. Initial margin continues to be treated as collateral and accounted for separately.

The fair values of derivatives are netted by clearing agent and/or by counterparty pursuant to the provisions of each of the Bank’s netting agreements. If these netted amounts are positive, they are classified as an asset and, if negative, as a liability.

Impaired Mortgage Loans Held for Portfolio and REO. The estimated fair values of impaired mortgage loans held for portfolio and real estate owned are determined based on values provided by a third party's retail-based AVM. The Bank adjusts the AVM value based on the amount it has historically received on liquidation.

Subjectivity of Estimates. Estimates of the fair value of financial assets and liabilities using the methods described above are highly subjective and require judgments regarding significant matters such as the amount and timing of future cash flows, prepayment speed assumptions, expected interest rate volatility, possible distributions of future interest rates used to value options, and the selection of discount rates that appropriately reflect market and credit risks. The use of different assumptions could have a material effect on the fair value estimates. These estimates are susceptible to material near term changes because they are made as of a specific point in time.

Fair Value Transfer, Policy

For instruments carried at fair value, the Bank reviews the fair value hierarchy classifications each quarter. Changes in the observability of the valuation attributes may result in a reclassification of certain financial assets or liabilities. Such reclassifications are reported as transfers in/out at fair value in the quarter in which the changes occur. Transfers are reported as of the beginning of the period.