Business and Basis of Presentation (Policies)	6 Months Ended
Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The unaudited interim condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). In management’s opinion, all material adjustments necessary for a fair statement of the financial condition, results of operations and cash flows of the Company, including its consolidated variable interest entities (VIEs), are reflected in the periods presented and are of a normal, recurring nature. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of 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. These unaudited interim condensed consolidated financial statements are as of June 30, 2023 and cover second quarter 2023, the three-month period ended June 30, 2022 (second quarter 2022), six months 2023 and the six-month period ended June 30, 2022 (six months 2022). Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but is not required for interim reporting purposes, has been condensed or omitted. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. Certain prior year balances have been reclassified to conform to the current period’s presentation.
Consolidation	The unaudited interim condensed consolidated financial statements include the accounts of AGL, its direct and indirect subsidiaries, and its consolidated financial guaranty VIEs (FG VIEs) and CIVs. See Note 8, Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles. Intercompany accounts and transactions between and among all consolidated entities have been eliminated.
Recent Accounting Standards Adopted	Recent Accounting Standards Adopted Targeted Improvements to the Accounting for Long-Duration Contracts In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2018-12, Financial Services - Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. The Company’s adoption of this ASU on January 1, 2023 did not have any effect on the Company’s consolidated financial statements.
Segment Information	The Company reports its results of operations in two segments: Insurance and Asset Management, separate from its Corporate division and the effects of consolidating FG VIEs and CIVs, which is consistent with the manner in which the Company’s chief operating decision maker (CODM) reviews the business to assess performance and allocate resources.
Fair Value Measurement	The Company carries a significant portion of its assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., exit price). The price represents the price available in the principal market for the asset or liability. If there is no principal market, then the price is based on a hypothetical market that maximizes the value received for an asset or minimizes the amount paid for a liability (i.e., the most advantageous market). Fair value is based on quoted market prices, where available. If listed prices or quotes are not available, fair value is based on either internally developed models that primarily use, as inputs, market-based or independently sourced market parameters, including but not limited to yield curves, interest rates and debt prices or with the assistance of an independent third party using a discounted cash flow approach and the third party’s proprietary pricing models. In addition to market information, models also incorporate transaction details, such as maturity of the instrument and contractual features designed to reduce the Company’s credit exposure, such as collateral rights as applicable. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments include amounts to reflect counterparty credit quality, the Company’s creditworthiness and constraints on liquidity. As markets and products develop and the pricing for certain products becomes more or less transparent, the Company may refine its methodologies and assumptions. During six months 2023, no changes were made to the Company’s valuation models that had, or are expected to have, a material impact on the Company’s condensed consolidated balance sheets or statements of operations and comprehensive income. The Company’s valuation methods produce fair values that may not be indicative of net realizable value or future fair values. The use of different methodologies or assumptions to determine fair value of certain financial instruments could result in a materially different estimate of fair value at the reporting date. The categorization within the fair value hierarchy is determined based on whether the inputs to valuation techniques used to measure fair value are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect Company estimates of market assumptions. The fair value hierarchy prioritizes model inputs into three broad levels, with Level 1 being the highest and Level 3 the lowest. An asset’s or liability’s categorization within the hierarchy is based on the lowest level of significant input to its valuation. Level 1—Quoted prices for identical instruments in active markets. The Company generally defines an active market as a market in which trading occurs at significant volumes. Active markets generally are more liquid and have a lower bid-ask spread than an inactive market. Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and observable inputs other than quoted prices, such as interest rates or yield curves and other inputs derived from or corroborated by observable market inputs. Level 3—Model derived valuations in which one or more significant inputs or significant value drivers are unobservable. Financial instruments are considered Level 3 when their values are determined using pricing models, discounted cash flow methodologies or similar techniques and at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value requires significant management judgment or estimation.

Business and Basis of Presentation (Policies)

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The unaudited interim condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). In management’s opinion, all material adjustments necessary for a fair statement of the financial condition, results of operations and cash flows of the Company, including its consolidated variable interest entities (VIEs), are reflected in the periods presented and are of a normal, recurring nature. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of 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.

These unaudited interim condensed consolidated financial statements are as of June 30, 2023 and cover second quarter 2023, the three-month period ended June 30, 2022 (second quarter 2022), six months 2023 and the six-month period ended June 30, 2022 (six months 2022). Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but is not required for interim reporting purposes, has been condensed or omitted. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all

disclosures required by GAAP. Certain prior year balances have been reclassified to conform to the current period’s presentation.

Consolidation

The unaudited interim condensed consolidated financial statements include the accounts of AGL, its direct and indirect subsidiaries, and its consolidated financial guaranty VIEs (FG VIEs) and CIVs. See Note 8, Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles. Intercompany accounts and transactions between and among all consolidated entities have been eliminated.

Recent Accounting Standards Adopted

Targeted Improvements to the Accounting for Long-Duration Contracts

In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2018-12, Financial Services - Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. The Company’s adoption of this ASU on January 1, 2023 did not have any effect on the Company’s consolidated financial statements.

Segment Information

The Company reports its results of operations in two segments: Insurance and Asset Management, separate from its Corporate division and the effects of consolidating FG VIEs and CIVs, which is consistent with the manner in which the Company’s chief operating decision maker (CODM) reviews the business to assess performance and allocate resources.

Fair Value Measurement

The Company carries a significant portion of its assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., exit price). The price represents the price available in the principal market for the asset or liability. If

there is no principal market, then the price is based on a hypothetical market that maximizes the value received for an asset or minimizes the amount paid for a liability (i.e., the most advantageous market).

Fair value is based on quoted market prices, where available. If listed prices or quotes are not available, fair value is based on either internally developed models that primarily use, as inputs, market-based or independently sourced market parameters, including but not limited to yield curves, interest rates and debt prices or with the assistance of an independent third party using a discounted cash flow approach and the third party’s proprietary pricing models. In addition to market information, models also incorporate transaction details, such as maturity of the instrument and contractual features designed to reduce the Company’s credit exposure, such as collateral rights as applicable.

Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments include amounts to reflect counterparty credit quality, the Company’s creditworthiness and constraints on liquidity. As markets and products develop and the pricing for certain products becomes more or less transparent, the Company may refine its methodologies and assumptions. During six months 2023, no changes were made to the Company’s valuation models that had, or are expected to have, a material impact on the Company’s condensed consolidated balance sheets or statements of operations and comprehensive income.

The Company’s valuation methods produce fair values that may not be indicative of net realizable value or future fair values. The use of different methodologies or assumptions to determine fair value of certain financial instruments could result in a materially different estimate of fair value at the reporting date.

The categorization within the fair value hierarchy is determined based on whether the inputs to valuation techniques used to measure fair value are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect Company estimates of market assumptions. The fair value hierarchy prioritizes model inputs into three broad levels, with Level 1 being the highest and Level 3 the lowest. An asset’s or liability’s categorization within the hierarchy is based on the lowest level of significant input to its valuation.

Level 1—Quoted prices for identical instruments in active markets. The Company generally defines an active market as a market in which trading occurs at significant volumes. Active markets generally are more liquid and have a lower bid-ask spread than an inactive market.

Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and observable inputs other than quoted prices, such as interest rates or yield curves and other inputs derived from or corroborated by observable market inputs.

Level 3—Model derived valuations in which one or more significant inputs or significant value drivers are unobservable. Financial instruments are considered Level 3 when their values are determined using pricing models, discounted cash flow methodologies or similar techniques and at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value requires significant management judgment or estimation.