Basis of Presentation and Significant Accounting Policies (Notes)	6 Months Ended
Jun. 30, 2016
Accounting Policies [Abstract]
Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]	2. BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES The Company has disclosed its significant accounting policies in Note 2. Significant Accounting Policies in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K/A for the year ended December 31, 2015. The following significant accounting policies provide an update to those included in the Company’s Annual Report on Form 10-K/A. Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial reporting and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for annual periods. These financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Annual Report on Form 10-K/A for the year ended December 31, 2015. The accompanying consolidated financial statements have not been audited by an independent registered public accounting firm in accordance with the standards of the Public Company Accounting Oversight Board (U.S.), but in the opinion of management such financial statements include all adjustments necessary for the fair presentation of the Company’s consolidated financial position and results of operations. All intercompany balances and transactions have been eliminated. The results of operations for the three and six months ended June 30, 2016 may not be indicative of the results that may be expected for the year ending December 31, 2016. The December 31, 2015 consolidated balance sheet was derived from audited financial statements. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. As additional information becomes available or actual amounts become determinable, the recorded estimates are revised and reflected in operating results. Reclassifications Certain reclassifications have been made to prior years' amounts to conform to the current year's presentation. Recently Adopted and Recently Issued Accounting Standards Adopted: Effective January 1, 2016, Ambac adopted the following accounting standards: ASU 2014-12, Compensation - Stock Compensation (Topics 718) - Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. Generally, share-based payment awards that require a specific performance target to be met also require an employee to render service until the performance target is achieved. However, in some cases, the terms of an award may provide that the performance target could be achieved after the employee completes the requisite service period. Under previous U.S. GAAP, there was no explicit guidance on how to account for share-based payment awards with performance targets that could be achieved after the requisite service period. This ASU is intended to resolve diversity in practice with respect to how the performance target is considered in the grant-date fair value of the award, which impacts the amount of compensation cost recognized over time. The ASU requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. As a result, the performance target would not be reflected in estimating the fair value of the award at the grant date. As Ambac previously followed the guidance in ASU 2014-12 for its share-based awards which have performance targets, the adoption of this ASU had no impact on Ambac's financial statements. ASU 2014-13, Consolidation (Topic 810): Measuring the Financial Assets and the Financial Liabilities of a Consolidated Collateralized Financing Entity. A collateralized financing entity ("CFE") is a variable interest entity with nominal or no equity that holds financial assets and issues beneficial interests in those financial assets. The beneficial interests, which are financial liabilities of the CFE, have contractual recourse only to the related assets of the CFE. Currently, a reporting entity that is required to consolidate a CFE may elect to measure the financial assets and financial liabilities of the CFE at fair value. Under the ASU, a reporting entity may elect to measure such assets and liabilities using either: i) the measurement principles in the Fair Value Measurement Topic of the ASC or ii) an alternative measurement approach specified in the ASU. The alternative measurement approach uses the more observable of either the fair value of the financial assets or financial liabilities to measure both. However, a reporting entity may not use the alternative measurement approach if it guarantees all or a portion of the CFE's beneficial interests. Furthermore, entities that do not (or may not) use the alternative measurement approach may not attribute any of the CFE's earnings to noncontrolling interests. The ASU is intended to address diversity in practice in accounting for the measurement difference between financial assets and financial liabilities of CFEs. Most of the CFEs consolidated by Ambac are the result of Ambac’s guarantee of the CFEs' respective beneficial interests. As a result, we may not apply the measurement alternative in this ASU to those CFEs. Previously, Ambac had one consolidated CFE where we elected to measure the financial assets and financial liabilities at fair value and where a portion of the CFEs earnings were attributed to noncontrolling interests. As a result, we have elected to use a modified retrospective approach in adopting this ASU and have reclassified $6,442 related to this CFE from noncontrolling interest to retained earnings on the balance sheet effective January 1, 2016. There was no impact on the Statement of Comprehensive Income. ASU 2014-16, Derivatives and Hedging (Topic 815): Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity. The objective of this ASU is to eliminate the existing diversity in practice in accounting for hybrid financial instruments issued in the form of a share. A hybrid financial instrument consists of a “host contract” into which one or more derivative terms have been embedded. The ASU requires an entity to consider the terms and features of the entire financial instrument, including the embedded derivative features, in order to determine whether the nature of the host contract is more akin to debt or to equity. Adoption of this ASU did not affect Ambac’s financial statements. ASU 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items. Extraordinary items are defined as both unusual in nature and infrequent in occurrence. Under previous guidance, a reporting entity was required to separately present and disclose extraordinary items. This ASU eliminates from current U.S. GAAP the concept of extraordinary items. However, the ASU retains the presentation and disclosure guidance for items that are unusual in nature or occur infrequently. Items that meet either or both of these criteria must be presented as a separate component on the face of the income statement or, alternatively, disclosed in the notes to the financial statements. Adoption of this ASU did not affect Ambac’s financial statements. ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis. This ASU makes changes to the variable interest ("VIE") model and voting interest ("VOE") model consolidation guidance. The main provisions of the ASU include the following: i) adding a requirement that limited partnerships and similar legal entities must provide partners with either substantive kick-out rights or substantive participating rights over the general partner to qualify as a VOE rather than a VIE; ii) eliminating the presumption that the general partner should consolidate a limited partnership; iii) eliminating certain conditions that need to be met when evaluating whether fees paid to a decision maker or service provider are considered a variable interest; iv) excluding certain fees paid to decision makers or service providers when evaluating which party is the primary beneficiary of a VIE; and v) revising how related parties are evaluated under the VIE guidance. Lastly, the ASU eliminates the indefinite deferral of FAS 167, which allowed reporting entities with interests in certain investment funds to follow previous guidance in FIN 46 (R). However, the ASU permanently exempts reporting entities from consolidating registered money market funds that operate in accordance with Rule 2a-7 of the Investment Company Act of 1940. Adoption of this ASU did not affect Ambac’s financial statements. ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30). This ASU simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts, rather than as a deferred asset. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this ASU. The ASU requires retrospective application to all prior periods presented. Adoption of this ASU did not have a material effect on Ambac’s financial statements. ASU 2015-07, Fair Value Measurement (Topic 820) - Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). Reporting entities are permitted to use net asset value ("NAV") as a practical expedient to measure the fair value of certain investments. Under previous GAAP, investments that use the NAV practical expedient to measure fair value were categorized within the fair value hierarchy as level 2 or level 3 investments depending on their redemption attributes, which has led to diversity in practice. This ASU will remove the requirement to categorize within the fair value hierarchy all investments that use the NAV practical expedient for fair value measurement purposes. Furthermore, the ASU will remove the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the NAV practical expedient. Upon adoption Ambac applied this ASU retrospectively to all prior periods presented, which was not material to Ambac's financial statements. Disclosures that were impacted by adoption of this ASU are shown in Note 7 - Fair Value Measurements. Issued: In March 2016, the FASB issued ASU 2016-06, Derivatives and Hedging (Topic 815) - Contingent Put and Call Options in Debt Instruments. Current accounting rules require that embedded derivatives be separated from the host contract in a financial instrument and accounted for separately as derivatives if certain criteria are met. One of these criteria is that the economic characteristics and risks of the embedded derivatives are not "clearly and closely related" to the host contract. The objective of the ASU is to resolve diversity in practice in assessing embedded contingent put and call options. The ASU clarifies what steps are required when assessing whether the economic characteristics and risk of put and call options are clearly and closely related to their debt host contracts. The ASU is effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, with early adoption permitted. The ASU must be applied on a modified retrospective basis to existing debt instruments as of the beginning of the fiscal year for which the amendments are effective. Ambac will adopt this ASU on January 1, 2017. Adoption of this ASU is not expected to have a material impact on Ambac's financial statements. In March 2016, the FASB issued ASU 2016-07, Investments-Equity Method and Joint Ventures (Topic 323) - Simplifying the Transition to the Equity Method of Accounting. This ASU eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations, and retained earnings retroactively as if the equity method had been in effect during all previous periods that the investment had been owned. The ASU will now require that at the date an available-for-sale equity security becomes qualified for the equity method of accounting, the reporting entity will recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 31, 2016, with early adoption permitted. The amendments should be applied prospectively upon adoption. Ambac may choose to early adopt this ASU to the extent we hold an available-for-sale equity security that becomes qualified for the equity method of accounting. Adoption of this ASU is not expected to have a material effect on Ambac's financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718) - Improvements to Employee Share-Based Payment Accounting. The objective of this ASU is to improve and simplify the accounting for employee share-based payment accounting. The amendments are as follows: (i) recognizing excess tax benefits and tax deficiencies as income tax expense, (ii) recognizing excess tax benefits regardless of whether it reduces taxes payable in the current period, (iii) classifying excess tax benefits related to share-based payments along with other income tax cash flows as an operating activity on the statement of cash flows, (iv) allowing companies to make an accounting policy election to either estimate forfeitures or account for forfeitures as they occur, for purposes of accruing compensation cost, (v) to qualify for equity classification treatment, permitting tax withholding by employees up to the maximum statutory tax rate and (vi) classifying cash paid by an employer to a taxing authority when directly withholding shares as a financing activity on the statement of cash flows. The ASU is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods, with early adoption permitted. Depending on the amendment, application will be prospective, retrospective or using a modified retrospective approach. Ambac will adopt this ASU on January 1, 2017. We are evaluating the impact of this ASU on Ambac's financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments. This ASU significantly affects how reporting entities will measure credit losses for financial assets that are not accounted for at fair value through net income, which include loans, debt securities, trade receivables, net investments in leases, and certain off-balance sheet credit exposures. For financial assets measured at amortized cost, the ASU replaces the "incurred loss" model, which generally delayed recognition of the full amount of credit losses until the loss was probable of occurring, with an "expected loss" model, which reflects an entity's current estimate of all expected credit losses. Expected credit losses for amortized cost assets will be recorded as a valuation allowance, with subsequent increases or decreases in the allowance reflected in the income statement each period. For available-for-sale debt securities, credit losses under the ASU will be measured similarly to current GAAP. However, under the ASU, credit losses for available-for-sale securities will be recorded as a valuation allowance (similar to the amortized cost assets approach described above), rather than as a direct write-down of the security as is required under current GAAP. As a result, improvements to estimated credit losses for available-for-sale debt securities will be recognized immediately in the income statement rather than as interest income over time. The ASU is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal year beginning after December 15, 2018. Ambac has not determined whether it will early adopt this ASU and we are currently evaluating its impact on Ambac's financial statements.

2. BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES

The Company has disclosed its significant accounting policies in Note 2. Significant Accounting Policies in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K/A for the year ended December 31, 2015. The following significant accounting policies provide an update to those included in the Company’s Annual Report on Form 10-K/A.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial reporting and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for annual periods. These financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Annual Report on Form 10-K/A for the year ended December 31, 2015. The accompanying consolidated financial statements have not been audited by an independent registered public accounting firm in accordance with the standards of the Public Company Accounting Oversight Board (U.S.), but in the opinion of management such financial statements include all adjustments necessary for the fair presentation of the Company’s consolidated financial position and results of operations. All intercompany balances and transactions have been eliminated. The results of operations for the three and six months ended June 30, 2016 may not be indicative of the results that may be expected for the year ending December 31, 2016. The December 31, 2015 consolidated balance sheet was derived from audited financial statements.

The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. As additional information becomes available or actual amounts become determinable, the recorded estimates are revised and reflected in operating results.

Reclassifications

Certain reclassifications have been made to prior years' amounts to conform to the current year's presentation.

Recently Adopted and Recently Issued Accounting Standards

Adopted:

Effective January 1, 2016, Ambac adopted the following accounting standards:

ASU 2014-12, Compensation - Stock Compensation (Topics 718) - Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. Generally, share-based payment awards that require a specific performance target to be met also require an employee to render service until the performance target is achieved. However, in some cases, the terms of an award may provide that the performance target could be achieved after the employee completes the requisite service period. Under previous U.S. GAAP, there was no explicit guidance on how to account for share-based payment awards with performance targets that could be achieved after the requisite service period. This ASU is intended to resolve diversity in practice with respect to how the performance target is considered in the grant-date fair value of the award, which impacts the amount of compensation cost recognized over time. The ASU requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. As a result, the performance target would not be reflected in estimating the fair value of the award at the grant date. As Ambac previously followed the guidance in ASU 2014-12 for its share-based awards which have performance targets, the adoption of this ASU had no impact on Ambac's financial statements.

ASU 2014-13, Consolidation (Topic 810): Measuring the Financial Assets and the Financial Liabilities of a Consolidated Collateralized Financing Entity. A collateralized financing entity ("CFE") is a variable interest entity with nominal or no equity that holds financial assets and issues beneficial interests in those financial assets. The beneficial interests, which are financial liabilities of the CFE, have contractual recourse only to the related assets of the CFE. Currently, a reporting entity that is required to consolidate a CFE may elect to measure the financial assets and financial liabilities of the CFE at fair value. Under the ASU, a reporting entity may elect to measure such assets and liabilities using either: i) the measurement principles in the Fair Value Measurement Topic of the ASC or ii) an alternative measurement approach specified in the ASU. The alternative measurement approach uses the more observable of either the fair value of the financial assets or financial liabilities to measure both. However, a reporting entity may not use the alternative measurement approach if it guarantees all or a portion of the CFE's beneficial interests. Furthermore, entities that do not (or may not) use the alternative measurement approach may not attribute any of the CFE's earnings to noncontrolling interests. The ASU is intended to address diversity in practice in accounting for the measurement difference between financial assets and financial liabilities of CFEs. Most of the CFEs consolidated by Ambac are the result of Ambac’s guarantee of the CFEs' respective beneficial interests. As a result, we may not apply the measurement alternative in this ASU to those CFEs. Previously, Ambac had one consolidated CFE where we elected to measure the financial assets and financial liabilities at fair value and where a portion of the CFEs earnings were attributed to noncontrolling interests. As a result, we have elected to use a modified retrospective approach in adopting this ASU and have reclassified $6,442 related to this CFE from noncontrolling interest to retained earnings on the balance sheet effective January 1, 2016. There was no impact on the Statement of Comprehensive Income.

ASU 2014-16, Derivatives and Hedging (Topic 815): Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity. The objective of this ASU is to eliminate the existing diversity in practice in accounting for hybrid financial instruments issued in the form of a share. A hybrid financial instrument consists of a “host contract” into which one or more derivative terms have been embedded. The ASU requires an entity to consider the terms and features of the entire financial instrument, including the embedded derivative features, in order to determine whether the nature of the host contract is more akin to debt or to equity. Adoption of this ASU did not affect Ambac’s financial statements.

ASU 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items. Extraordinary items are defined as both unusual in nature and infrequent in occurrence. Under previous guidance, a reporting entity was required to separately present and disclose extraordinary items. This ASU eliminates from current U.S. GAAP the concept of extraordinary items. However, the ASU retains the presentation and disclosure guidance for items that are unusual in nature or occur infrequently. Items that meet either or both of these criteria must be presented as a separate component on the face of the income statement or, alternatively, disclosed in the notes to the financial statements. Adoption of this ASU did not affect Ambac’s financial statements.

ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis. This ASU makes changes to the variable interest ("VIE") model and voting interest ("VOE") model consolidation guidance. The main provisions of the ASU include the following: i) adding a requirement that limited partnerships and similar legal entities must provide partners with either substantive kick-out rights or substantive participating rights over the general partner to qualify as a VOE rather than a VIE; ii) eliminating the presumption that the general partner should consolidate a limited partnership; iii) eliminating certain conditions that need to be met when evaluating whether fees paid to a decision maker or service provider are considered a variable interest; iv) excluding certain fees paid to decision makers or service providers when evaluating which party is the primary beneficiary of a VIE; and v) revising how related parties are evaluated under the VIE guidance. Lastly, the ASU eliminates the indefinite deferral of FAS 167, which allowed reporting entities with interests in certain investment funds to follow previous guidance in FIN 46 (R). However, the ASU permanently exempts reporting entities from consolidating registered money market funds that operate in accordance with Rule 2a-7 of the Investment Company Act of 1940. Adoption of this ASU did not affect Ambac’s financial statements.

ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30). This ASU simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts, rather than as a deferred asset. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this ASU. The ASU requires retrospective application to all prior periods presented. Adoption of this ASU did not have a material effect on Ambac’s financial statements.

ASU 2015-07, Fair Value Measurement (Topic 820) - Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). Reporting entities are permitted to use net asset value ("NAV") as a practical expedient to measure the fair value of certain investments. Under previous GAAP, investments that use the NAV practical expedient to measure fair value were categorized within the fair value hierarchy as level 2 or level 3 investments depending on their redemption attributes, which has led to diversity in practice. This ASU will remove the requirement to categorize within the fair value hierarchy all investments that use the NAV practical expedient for fair value measurement purposes. Furthermore, the ASU will remove the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the NAV practical expedient. Upon adoption Ambac applied this ASU retrospectively to all prior periods presented, which was not material to Ambac's financial statements. Disclosures that were impacted by adoption of this ASU are shown in Note 7 - Fair Value Measurements.

Issued:

In March 2016, the FASB issued ASU 2016-06, Derivatives and Hedging (Topic 815) - Contingent Put and Call Options in Debt Instruments. Current accounting rules require that embedded derivatives be separated from the host contract in a financial instrument and accounted for separately as derivatives if certain criteria are met. One of these criteria is that the economic characteristics and risks of the embedded derivatives are not "clearly and closely related" to the host contract. The objective of the ASU is to resolve diversity in practice in assessing embedded contingent put and call options. The ASU clarifies what steps are required when assessing whether the economic characteristics and risk of put and call options are clearly and closely related to their debt host contracts. The ASU is effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years, with early adoption permitted. The ASU must be applied on a modified retrospective basis to existing debt instruments as of the beginning of the fiscal year for which the amendments are effective. Ambac will adopt this ASU on January 1, 2017. Adoption of this ASU is not expected to have a material impact on Ambac's financial statements.

In March 2016, the FASB issued ASU 2016-07, Investments-Equity Method and Joint Ventures (Topic 323) - Simplifying the Transition to the Equity Method of Accounting. This ASU eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations, and retained earnings retroactively as if the equity method had been in effect during all previous periods that the investment had been owned. The ASU will now require that at the date an available-for-sale equity security becomes qualified for the equity method of accounting, the reporting entity will recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 31, 2016, with early adoption permitted. The amendments should be applied prospectively upon adoption. Ambac may choose to early adopt this ASU to the extent we hold an available-for-sale equity security that becomes qualified for the equity method of accounting. Adoption of this ASU is not expected to have a material effect on Ambac's financial statements.

In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718) - Improvements to Employee Share-Based Payment Accounting. The objective of this ASU is to improve and simplify the accounting for employee share-based payment accounting. The amendments are as follows: (i) recognizing excess tax benefits and tax deficiencies as income tax expense, (ii) recognizing excess tax benefits regardless of whether it reduces taxes payable in the current period, (iii) classifying excess tax benefits related to share-based payments along with other income tax cash flows as an operating activity on the statement of cash flows, (iv) allowing companies to make an accounting policy election to either estimate forfeitures or account for forfeitures as they occur, for purposes of accruing compensation cost, (v) to qualify for equity classification treatment, permitting tax withholding by employees up to the maximum statutory tax rate and (vi) classifying cash paid by an employer to a taxing authority when directly withholding shares as a financing activity on the statement of cash flows. The ASU is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods, with early adoption permitted. Depending on the amendment, application will be prospective, retrospective or using a modified retrospective approach. Ambac will adopt this ASU on January 1, 2017. We are evaluating the impact of this ASU on Ambac's financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments. This ASU significantly affects how reporting entities will measure credit losses for financial assets that are not accounted for at fair value through net income, which include loans, debt securities, trade receivables, net investments in leases, and certain off-balance sheet credit exposures. For financial assets measured at amortized cost, the ASU replaces the "incurred loss" model, which generally delayed recognition of the full amount of credit losses until the loss was probable of occurring, with an "expected loss" model, which reflects an entity's current estimate of all expected credit losses. Expected credit losses for amortized cost assets will be recorded as a valuation allowance, with subsequent increases or decreases in the allowance reflected in the income statement each period. For available-for-sale debt securities, credit losses under the ASU will be measured similarly to current GAAP. However, under the ASU, credit losses for available-for-sale securities will be recorded as a valuation allowance (similar to the amortized cost assets approach described above), rather than as a direct write-down of the security as is required under current GAAP. As a result, improvements to estimated credit losses for available-for-sale debt securities will be recognized immediately in the income statement rather than as interest income over time. The ASU is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal year beginning after December 15, 2018. Ambac has not determined whether it will early adopt this ASU and we are currently evaluating its impact on Ambac's financial statements.