Nature of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]
Nature of Business	Nature of Business ACI Worldwide, Inc., a Delaware corporation, and its subsidiaries (collectively referred to as “ACI” or the “Company”) develop, market, install, and support a broad line of software products and services primarily focused on facilitating electronic payments. In addition to its own products, the Company distributes or acts as a sales agent for software developed by third parties. These products and services are used principally by banks and intermediaries, merchants, and billers, both in domestic and international markets.
Consolidated Financial Statements	Consolidated Financial StatementsThe consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated.
Capital Stock	Capital Stock The Company’s outstanding capital stock consists of a single class of common stock. Each share of common stock is entitled to one vote for each matter subject to a stockholder’s vote and to dividends, if and when declared by the board of directors (the “board”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash EquivalentsThe Company considers all highly liquid investments with original maturities of three months or less to be cash equivalents. The Company’s cash and cash equivalents includes holdings in checking, savings, money market, and overnight sweep accounts, all of which have daily maturities, as well as time deposits with maturities of three months or less at the date of purchase.
Revision of Prior Period Financial Statements	Revision of Prior Period Financial Statements As of December 31, 2021, the Company has revised the previously reported consolidated statements of cash flows to include settlement deposits in total cash and cash equivalents and settlement receivables and settlement liabilities net activity in cash flows from financing activities, both of which were previously included in cash flows from operating activities. This immaterial revision did not have an effect on its previously reported consolidated balance sheets, statements of operations, statements of comprehensive income, or statements of stockholders' equity.
Settlement Assets and Liabilities	Settlement Assets and Liabilities Individuals and businesses settle their obligations to the Company’s various Biller clients using credit or debit cards or via automated clearing house (“ACH”) payments. The Company creates a receivable for the amount due from the credit or debit card processor and an offsetting payable to the client. Upon confirmation that the funds have been received, the Company settles the obligation to the client. Due to timing, in some instances, the Company may (1) receive the funds into bank accounts controlled by and in the Company’s name that are not disbursed to its clients by the end of the day, resulting in a settlement deposit on the Company’s books and (2) disburse funds to its clients in advance of receiving funds from the credit or debit card processor, resulting in a net settlement receivable position.
Off Balance Sheet Settlement Accounts	Off Balance Sheet Settlement AccountsThe Company also enters into agreements with certain Biller clients to process payment funds on their behalf. When an ACH or automated teller machine network payment transaction is processed, a transaction is initiated to withdraw funds from the designated source account and deposit them into a settlement account, which is a trust account maintained for the benefit of the Company’s clients. A simultaneous transaction is initiated to transfer funds from the settlement account to the intended destination account. These “back to back” transactions are designed to settle at the same time, usually overnight, such that the Company receives the funds from the source at the same time as it sends the funds to their destination. However, due to the transactions being with various financial institutions there may be timing differences that result in float balances. These funds are maintained in accounts for the benefit of the client which is separate from the Company’s corporate assets. As the Company does not take ownership of the funds, these settlement accounts are not included in the Company’s balance sheet. The Company is entitled to interest earned on the fund balances. The collection of interest on these settlement accounts is considered in the Company’s determination of its fee structure for clients and represents a portion of the payment for services performed by the Company.
Property and Equipment	Property and EquipmentProperty and equipment are stated at cost. Depreciation of these assets is generally computed using the straight-line method over their estimated useful lives based on asset class.
Software	Software Software may be for internal use or for resale. Costs related to certain software, which is for resale, are capitalized in accordance with Accounting Standards Codification (“ASC”) 985-20, Costs of Software to be Sold, Leased, or Marketed, when the resulting product reaches technological feasibility. The Company generally determines technological feasibility when it has a detailed program design that takes product function, feature and technical requirements to their most detailed, logical form and is ready for coding. The Company does not typically capitalize costs related to software for resale as technological feasibility generally coincides with general availability of the software. The Company capitalizes the costs of software developed or obtained for internal use in accordance with ASC 350-40, Internal Use Software. The Company expenses all costs incurred during the preliminary project stage of its development and capitalizes the costs incurred during the application development stage. Costs incurred relating to upgrades and enhancements to the software are capitalized if it is determined that these upgrades or enhancements add additional functionality to the software. Costs incurred during the application development stage include purchased software licenses, implementation costs, consulting costs, and payroll-related costs for projects that qualify for capitalization. All other costs, primarily related to maintenance and minor software fixes, are expensed as incurred. Amortization of software for resale is determined on a product-by-product basis and begins when the product is available for licensing to customers. The annual amortization is computed using the greater of (a) the ratio of current gross revenues to the total of current and future gross revenues expected to be derived from the software or (b) the straight-line method over the remaining estimated useful life of generally five to ten years, including the period being reported on. Due to competitive pressures, it may be possible that the estimates of future gross revenue or remaining estimated useful life of the software will be reduced significantly. As a result, the carrying amount of the software may be reduced accordingly. Amortization of internal-use software is generally computed using the straight-line method over estimated useful lives of three to eight years.
Business Combinations	Business Combinations The Company applies the provisions of ASC 805, Business Combinations, in the accounting for its acquisitions. It requires the Company to recognize separately from goodwill the assets acquired and the liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred and the net of the acquisition date fair values of the assets acquired and the liabilities assumed. While the Company uses its best estimates and assumptions to accurately value assets acquired and liabilities assumed at the acquisition date, its estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, it records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to our consolidated statements of operations. Critical estimates in valuing certain intangible assets include but are not limited to future expected cash flows from customer relationships, covenants not to compete and acquired developed technologies, brand awareness and market position, as well as assumptions about the period of time the brand will continue to be used in our product portfolio, and discount rates. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Other estimates associated with the accounting for acquisitions may change as additional information becomes available regarding the assets acquired and liabilities assumed.
Fair Value	Fair Value ASC 820, Fair Value Measurements and Disclosures, (“ASC 820”) defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. ASC 820 establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows: •Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. •Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means. •Level 3 Inputs – Unobservable inputs for determining the fair values of assets or liabilities that reflect an entity’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. The fair value of the Company’s Credit Agreement approximates the carrying value due to the floating interest rate (Level 2 of the fair value hierarchy). The Company measures the fair value of its Senior Notes based on Level 2 inputs, which include quoted market prices and interest rate spreads of similar securities. The fair value of the Company’s 5.750% Senior Notes due 2026 (“2026 Notes”) was $419.0 million and $424.5 million as of December 31, 2021 and 2020, respectively. The fair values of cash and cash equivalents approximate the carrying values due to the short period of time to maturity (Level 2 of the fair value hierarchy).
Goodwill and Other Intangibles	Goodwill and Other Intangibles In accordance with ASC 350, Intangibles – Goodwill and Other, the Company assesses goodwill for impairment annually during the fourth quarter of its fiscal year using October 1 balances or when there is evidence that events or changes in circumstances indicate that the carrying amount of the asset may not be recovered. The Company evaluates goodwill at the reporting unit level, and as discussed in Note 10, Segment Information, in January 2021, it announced a change in organizational structure to better align with the Company’s strategic direction. This change also resulted in a change in reporting units to coincide with the new operating segments—Banks, Merchants, and Billers. The Company allocated goodwill to the new reporting units using a relative fair value approach with total goodwill of $1.3 billion allocated $725.9 million to Banks, $137.3 million to Merchants, and $417.0 million to Billers. In addition, the Company performed an assessment of potential goodwill impairment for all reporting units immediately prior to the reallocation and determined that no impairment was indicated. The key assumptions used in the discounted cash flow valuation model include discount rates, growth rates, cash flow projections and terminal value rates. Discount rates, growth rates, and cash flow projections are the most sensitive and susceptible to change, as they require significant management judgment. Discount rates are determined by using a weighted average cost of capital (“WACC”). The WACC considers market and industry data as well as company-specific risk factors. Operational management, considering industry and company-specific historical and projected data, develops growth rates and cash flow projections for each reporting unit. Terminal value rate determination follows common methodology of capturing the present value of perpetual cash flow estimates beyond the last projected period, assuming a constant WACC and low, long-term growth rates. If the recoverability test indicates potential impairment, the Company calculates an implied fair value of goodwill for the reporting unit. The implied fair value of goodwill is determined in a manner similar to how goodwill is calculated in a business combination. If the implied fair value of goodwill exceeds the carrying value of goodwill assigned to the reporting unit, there is no impairment. If the carrying value of goodwill assigned to the reporting unit exceeds the implied fair value of the goodwill, an impairment charge is recorded to write down the carrying value. The calculated fair value substantially exceeded the current carrying value for all reporting units for all periods. Other intangible assets, which include customer relationships and trademarks and trade names, are amortized using the straight-line method over periods ranging from four to 20 years. The Company reviews its other intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.
Equity Method Investments	Equity Method InvestmentIn July 2019, the Company invested $18.3 million for a 30% non-controlling financial interest in a payment technology and services company in India. The Company accounted for this investment using the equity method in accordance with ASC 323, Investments - Equity Method and Joint Ventures. The Company records its share of earnings and losses in the investment on a one-quarter lag basis. Accordingly, the Company recorded an investment of $19.3 million, which is included in other noncurrent assets in the consolidated balance sheet as of December 31, 2021 and 2020.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of a long-lived asset group may not be recoverable. An impairment loss is recorded if the sum of the future cash flows expected to result from the use of the asset (undiscounted and without interest charges) is less than the carrying amount of the asset. The amount of the impairment charge is measured based upon the fair value of the asset group.
Treasury Stock	Treasury Stock The Company accounts for shares of its common stock that are repurchased without intent to retire as treasury stock. Such shares are recorded at cost and reflected separately on the consolidated balance sheets as a reduction of stockholders’ equity. The Company issues shares of treasury stock upon exercise of stock options, issuance of restricted share units, payment of earned performance shares, and for issuances of common stock pursuant to the Company’s employee stock purchase plan. For purposes of determining the cost of the treasury shares re-issued, the Company uses the average cost method.
Stock-Based Compensation Plans	Stock-Based Compensation Plans In accordance with ASC 718, Compensation – Stock Compensation, ("ASC 718") the Company recognizes stock-based compensation expense for awards that are probable of vesting on a straight-line basis over the requisite service period of the award, which is generally the vesting term. Stock-based compensation expense is recorded in operating expenses depending on where the respective individual’s compensation is recorded. To determine the grant date fair value of total shareholder return awards (“TSRs”), a Monte Carlo simulation model was used. The assumptions utilized in the Monte Carlo simulation models, as well as the description of the plans the stock-based awards are granted under, are described in further detail in Note 6, Stock-Based Compensation Plans.
Translation of Foreign Currencies	Translation of Foreign Currencies The Company’s foreign subsidiaries typically use the local currency of the countries in which they are located as their functional currency. Their assets and liabilities are translated into U.S. dollars at the exchange rates in effect at the balance sheet date. Revenues and expenses are translated at the average exchange rates during the period. Translation gains and losses are reflected in the consolidated financial statements as a component of accumulated other comprehensive income (loss). Transaction gains and losses, including those related to intercompany accounts, that are not considered to be of a long-term investment nature are included in the determination of net income. Transaction gains and losses, including those related to intercompany accounts, that are considered to be of a long-term investment nature are reflected in the consolidated financial statements as a component of accumulated other comprehensive income (loss).
Income Taxes	Income Taxes The provision for income taxes is computed using the asset and liability method, under which deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities. Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company periodically assesses its tax exposures and establishes, or adjusts, estimated unrecognized tax benefits for probable assessments by taxing authorities, including the Internal Revenue Service, and various foreign and state authorities. Such unrecognized tax benefits represent the estimated provision for income taxes expected to ultimately be paid.
New Accounting Standards Recently Adopted and Recently Issued Accounting Standards Not Yet Effective	New Accounting Standards Recently AdoptedIn December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, as part of its initiative to reduce complexity in accounting standards. The amendments in this update simplify the accounting for income taxes by removing certain exceptions within ASC 740, as well as clarify and simplify other aspects of the accounting for income taxes to promote consistency among reporting entities. ASU 2019-12 is effective for annual and interim periods beginning after December 15, 2020. The Company adopted ASU 2019-12 as of January 1, 2021. The adoption of ASU 2019-12 did not have a material impact on the Company's consolidated financial statements.
Earnings Per Share	Basic earnings per share is computed in accordance with ASC 260, Earnings per Share, based on weighted average outstanding common shares. Diluted earnings per share is computed based on basic weighted average outstanding common shares adjusted for the dilutive effect of stock options, RSUs, and certain contingently issuable shares for which performance targets have been achieved.
Segment Information	In January 2021, the Company made a change in organizational structure to align with its strategic direction. As a result of this change, the Company reassessed its segment reporting structure due to changes in how the Company's chief operating decision maker ("CODM") assesses the Company's performance and allocates resources. Beginning in the first quarter of 2021, the Company reports financial performance based on its new operating segments, Banks, Merchants, and Billers, and analyzes Segment Adjusted EBITDA as a measure of segment profitability. The Company’s Chief Executive Officer is also CODM. The CODM, together with other senior management personnel, focus their review on consolidated financial information and the allocation of resources based on operating results, including revenues and Segment Adjusted EBITDA, for each segment, separate from corporate operations. No operating segments have been aggregated to form the reportable segments. Banks. ACI provides payment solutions to large and mid-size banks globally for retail banking, real time, digital, and other payment services. These solutions transform banks’ complex payment environments to speed time to market, reduce costs, and deliver a consistent experience to customers across channels while enabling them to prevent and rapidly react to fraudulent activity. In addition, they enable banks to meet the requirements of different real-time payments schemes and to quickly create differentiated products to meet consumer, business, and merchant demands. Merchants. ACI’s support of merchants globally includes Tier 1 and Tier 2 merchants, online-only merchants and the payment service providers, independent selling organizations, value-added resellers, and acquirers who service them. These customers operate in a variety of verticals, including general merchandise, grocery, hospitality, dining, transportation, and others. The Company's solutions provide merchants with a secure, omni-channel payments platform that gives them independence from third-party payment providers. They also offer secure solutions to online-only merchants that provide consumers with a convenient and seamless way to shop. Billers. Within the billers segment, ACI provides electronic bill presentment and payment (“EBPP”) services to companies operating in the consumer finance, insurance, healthcare, higher education, utility, government, and mortgage categories. The solutions enable these customers to support a wide range of payment options and provide a convenient consumer payments experience that drives consumer loyalty and increases revenue. Revenue is attributed to the reportable segments based upon customer. Expenses are attributed to the reportable segments in one of three methods, (1) direct costs of the segment, (2) labor costs that can be attributed based upon time tracking for individual projects, or (3) costs that are allocated. Allocated costs are generally marketing and sales related activities. Segment Adjusted EBITDA is the measure reported to the CODM for purposes of making decisions on allocating resources and assessing the performance of the Company’s segments, and therefore, Segment Adjusted EBITDA is presented in conformity with ASC 280, Segment Reporting. Segment Adjusted EBITDA is defined as earnings (loss) from operations before interest, income tax expense (benefit), depreciation and amortization (“EBITDA”) adjusted to exclude net other income (expense). Corporate and unallocated expenses includes global facilities and information technology costs and long-term product roadmap expenses in addition to corporate overhead costs that are not allocated to reportable segments. The overhead costs relate to human resources, finance, legal, accounting, and merger and acquisition activity. These costs along with depreciation and amortization and stock-based compensation are not considered when management evaluates segment performance.

Nature of Business and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

ACI Worldwide, Inc., a Delaware corporation, and its subsidiaries (collectively referred to as “ACI” or the “Company”) develop, market, install, and support a broad line of software products and services primarily focused on facilitating electronic payments. In addition to its own products, the Company distributes or acts as a sales agent for software developed by third parties. These products and services are used principally by banks and intermediaries, merchants, and billers, both in domestic and international markets.

Consolidated Financial Statements

Consolidated Financial StatementsThe consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated.

Capital Stock

The Company’s outstanding capital stock consists of a single class of common stock. Each share of common stock is entitled to one vote for each matter subject to a stockholder’s vote and to dividends, if and when declared by the board of directors (the “board”).

Use of Estimates

The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash and Cash EquivalentsThe Company considers all highly liquid investments with original maturities of three months or less to be cash equivalents. The Company’s cash and cash equivalents includes holdings in checking, savings, money market, and overnight sweep accounts, all of which have daily maturities, as well as time deposits with maturities of three months or less at the date of purchase.

Revision of Prior Period Financial Statements

As of December 31, 2021, the Company has revised the previously reported consolidated statements of cash flows to include settlement deposits in total cash and cash equivalents and settlement receivables and settlement liabilities net activity in cash flows from financing activities, both of which were previously included in cash flows from operating activities. This immaterial revision did not have an effect on its previously reported consolidated balance sheets, statements of operations, statements of comprehensive income, or statements of stockholders' equity.

Settlement Assets and Liabilities

Individuals and businesses settle their obligations to the Company’s various Biller clients using credit or debit cards or via automated clearing house (“ACH”) payments. The Company creates a receivable for the amount due from the credit or debit card processor and an offsetting payable to the client. Upon confirmation that the funds have been received, the Company settles the obligation to the client. Due to timing, in some instances, the Company may (1) receive the funds into bank accounts controlled by and in the Company’s name that are not disbursed to its clients by the end of the day, resulting in a settlement deposit on the Company’s books and (2) disburse funds to its clients in advance of receiving funds from the credit or debit card processor, resulting in a net settlement receivable position.

Off Balance Sheet Settlement Accounts

Off Balance Sheet Settlement AccountsThe Company also enters into agreements with certain Biller clients to process payment funds on their behalf. When an ACH or automated teller machine network payment transaction is processed, a transaction is initiated to withdraw funds from the designated source account and deposit them into a settlement account, which is a trust account maintained for the benefit of the Company’s clients. A simultaneous transaction is initiated to transfer funds from the settlement account to the intended destination account. These “back to back” transactions are designed to settle at the same time, usually overnight, such that the Company receives the funds from the source at the same time as it sends the funds to their destination. However, due to the transactions being with various financial institutions there may be timing differences that result in float balances. These funds are maintained in accounts for the benefit of the client which is separate from the Company’s corporate assets. As the Company does not take ownership of the funds, these settlement accounts are not included in the Company’s balance sheet. The Company is entitled to interest earned on the fund balances. The collection of interest on these settlement accounts is considered in the Company’s determination of its fee structure for clients and represents a portion of the payment for services performed by the Company.

Property and Equipment

Property and EquipmentProperty and equipment are stated at cost. Depreciation of these assets is generally computed using the straight-line method over their estimated useful lives based on asset class.

Software

Software may be for internal use or for resale. Costs related to certain software, which is for resale, are capitalized in accordance with Accounting Standards Codification (“ASC”) 985-20, Costs of Software to be Sold, Leased, or Marketed, when the resulting product reaches technological feasibility. The Company generally determines technological feasibility when it has a detailed program design that takes product function, feature and technical requirements to their most detailed, logical form and is ready for coding. The Company does not typically capitalize costs related to software for resale as technological feasibility generally coincides with general availability of the software. The Company capitalizes the costs of software developed or obtained for internal use in accordance with ASC 350-40, Internal Use Software. The Company expenses all costs incurred during the preliminary project stage of its development and capitalizes the costs incurred during the application development stage. Costs incurred relating to upgrades and enhancements to the software are capitalized if it is determined that these upgrades or enhancements add additional functionality to the software. Costs incurred during the application development stage include purchased software licenses, implementation costs, consulting costs, and payroll-related costs for projects that qualify for capitalization. All other costs, primarily related to maintenance and minor software fixes, are expensed as incurred.

Amortization of software for resale is determined on a product-by-product basis and begins when the product is available for licensing to customers. The annual amortization is computed using the greater of (a) the ratio of current gross revenues to the total of current and future gross revenues expected to be derived from the software or (b) the straight-line method over the remaining estimated useful life of generally five to ten years, including the period being reported on. Due to competitive pressures, it may be possible that the estimates of future gross revenue or remaining estimated useful life of the software will be reduced significantly. As a result, the carrying amount of the software may be reduced accordingly. Amortization of internal-use software is generally computed using the straight-line method over estimated useful lives of three to eight years.

Business Combinations

The Company applies the provisions of ASC 805, Business Combinations, in the accounting for its acquisitions. It requires the Company to recognize separately from goodwill the assets acquired and the liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred and the net of the acquisition date fair values of the assets acquired and the liabilities assumed. While the Company uses its best estimates and assumptions to accurately value assets acquired and liabilities assumed at the acquisition date, its estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, it records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to our consolidated statements of operations.

Critical estimates in valuing certain intangible assets include but are not limited to future expected cash flows from customer relationships, covenants not to compete and acquired developed technologies, brand awareness and market position, as well as assumptions about the period of time the brand will continue to be used in our product portfolio, and discount rates. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates.

Other estimates associated with the accounting for acquisitions may change as additional information becomes available regarding the assets acquired and liabilities assumed.

Fair Value

ASC 820, Fair Value Measurements and Disclosures, (“ASC 820”) defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. ASC 820 establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:

•Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

•Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means.

•Level 3 Inputs – Unobservable inputs for determining the fair values of assets or liabilities that reflect an entity’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities.

The fair value of the Company’s Credit Agreement approximates the carrying value due to the floating interest rate (Level 2 of the fair value hierarchy). The Company measures the fair value of its Senior Notes based on Level 2 inputs, which include quoted market prices and interest rate spreads of similar securities. The fair value of the Company’s 5.750% Senior Notes due 2026 (“2026 Notes”) was $419.0 million and $424.5 million as of December 31, 2021 and 2020, respectively.

The fair values of cash and cash equivalents approximate the carrying values due to the short period of time to maturity (Level 2 of the fair value hierarchy).

Goodwill and Other Intangibles

In accordance with ASC 350, Intangibles – Goodwill and Other, the Company assesses goodwill for impairment annually during the fourth quarter of its fiscal year using October 1 balances or when there is evidence that events or changes in circumstances indicate that the carrying amount of the asset may not be recovered. The Company evaluates goodwill at the reporting unit level, and as discussed in Note 10, Segment Information, in January 2021, it announced a change in organizational structure to better align with the Company’s strategic direction. This change also resulted in a change in reporting units to coincide with the new operating segments—Banks, Merchants, and Billers. The Company allocated goodwill to the new reporting units using a relative fair value approach with total goodwill of $1.3 billion allocated $725.9 million to Banks, $137.3 million to Merchants, and $417.0 million to Billers. In addition, the Company performed an assessment of potential goodwill impairment for all reporting units immediately prior to the reallocation and determined that no impairment was indicated.

The key assumptions used in the discounted cash flow valuation model include discount rates, growth rates, cash flow projections and terminal value rates. Discount rates, growth rates, and cash flow projections are the most sensitive and susceptible to change, as they require significant management judgment. Discount rates are determined by using a weighted average cost of capital (“WACC”). The WACC considers market and industry data as well as company-specific risk factors. Operational management, considering industry and company-specific historical and projected data, develops growth rates and cash flow projections for each reporting unit. Terminal value rate determination follows common methodology of capturing the present value of perpetual cash flow estimates beyond the last projected period, assuming a constant WACC and low, long-term growth rates. If the recoverability test indicates potential impairment, the Company calculates an implied fair value of goodwill for the reporting unit. The implied fair value of goodwill is determined in a manner similar to how goodwill is calculated in a business combination. If the implied fair value of goodwill exceeds the carrying value of goodwill assigned to the reporting unit, there is no impairment. If the carrying value of goodwill assigned to the reporting unit exceeds the implied fair value of the goodwill, an impairment charge is recorded to write down the carrying value. The calculated fair value substantially exceeded the current carrying value for all reporting units for all periods.

Other intangible assets, which include customer relationships and trademarks and trade names, are amortized using the straight-line method over periods ranging from four to 20 years. The Company reviews its other intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.

Equity Method Investments

Equity Method InvestmentIn July 2019, the Company invested $18.3 million for a 30% non-controlling financial interest in a payment technology and services company in India. The Company accounted for this investment using the equity method in accordance with ASC 323, Investments - Equity Method and Joint Ventures. The Company records its share of earnings and losses in the investment on a one-quarter lag basis. Accordingly, the Company recorded an investment of $19.3 million, which is included in other noncurrent assets in the consolidated balance sheet as of December 31, 2021 and 2020.

Impairment of Long-Lived Assets

The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of a long-lived asset group may not be recoverable. An impairment loss is recorded if the sum of the future cash flows expected to result from the use of the asset (undiscounted and without interest charges) is less than the carrying amount of the asset. The amount of the impairment charge is measured based upon the fair value of the asset group.

Treasury Stock

The Company accounts for shares of its common stock that are repurchased without intent to retire as treasury stock. Such shares are recorded at cost and reflected separately on the consolidated balance sheets as a reduction of stockholders’ equity. The Company issues shares of treasury stock upon exercise of stock options, issuance of restricted share units, payment of earned performance shares, and for issuances of common stock pursuant to the Company’s employee stock purchase plan. For purposes of determining the cost of the treasury shares re-issued, the Company uses the average cost method.

Stock-Based Compensation Plans

In accordance with ASC 718, Compensation – Stock Compensation, ("ASC 718") the Company recognizes stock-based compensation expense for awards that are probable of vesting on a straight-line basis over the requisite service period of the award, which is generally the vesting term. Stock-based compensation expense is recorded in operating expenses depending on where the respective individual’s compensation is recorded. To determine the grant date fair value of total shareholder return awards (“TSRs”), a Monte Carlo simulation model was used. The assumptions utilized in the Monte Carlo simulation models, as well as the description of the plans the stock-based awards are granted under, are described in further detail in Note 6, Stock-Based Compensation Plans.

Translation of Foreign Currencies

The Company’s foreign subsidiaries typically use the local currency of the countries in which they are located as their functional currency. Their assets and liabilities are translated into U.S. dollars at the exchange rates in effect at the balance sheet date. Revenues and expenses are translated at the average exchange rates during the period. Translation gains and losses are reflected in the consolidated financial statements as a component of accumulated other comprehensive income (loss). Transaction gains and losses, including those related to intercompany accounts, that are not considered to be of a long-term investment nature are included in the determination of net income. Transaction gains and losses, including those related to intercompany accounts, that are considered to be of a long-term investment nature are reflected in the consolidated financial statements as a component of accumulated other comprehensive income (loss).

Income Taxes

The provision for income taxes is computed using the asset and liability method, under which deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities. Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion or all of the deferred tax assets will not be realized.

The Company periodically assesses its tax exposures and establishes, or adjusts, estimated unrecognized tax benefits for probable assessments by taxing authorities, including the Internal Revenue Service, and various foreign and state authorities. Such unrecognized tax benefits represent the estimated provision for income taxes expected to ultimately be paid.

New Accounting Standards Recently Adopted and Recently Issued Accounting Standards Not Yet Effective

New Accounting Standards Recently AdoptedIn December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, as part of its initiative to reduce complexity in accounting standards. The amendments in this update simplify the accounting for income taxes by removing certain exceptions within ASC 740, as well as clarify and simplify other aspects of the accounting for income taxes to promote consistency among reporting entities. ASU 2019-12 is effective for annual and interim periods beginning after December 15, 2020. The Company adopted ASU 2019-12 as of January 1, 2021. The adoption of ASU 2019-12 did not have a material impact on the Company's consolidated financial statements.

Earnings Per Share

Basic earnings per share is computed in accordance with ASC 260, Earnings per Share, based on weighted average outstanding common shares. Diluted earnings per share is computed based on basic weighted average outstanding common shares adjusted for the dilutive effect of stock options, RSUs, and certain contingently issuable shares for which performance targets have been achieved.

Segment Information

In January 2021, the Company made a change in organizational structure to align with its strategic direction. As a result of this change, the Company reassessed its segment reporting structure due to changes in how the Company's chief operating decision maker ("CODM") assesses the Company's performance and allocates resources. Beginning in the first quarter of 2021, the Company reports financial performance based on its new operating segments, Banks, Merchants, and Billers, and analyzes Segment Adjusted EBITDA as a measure of segment profitability.

The Company’s Chief Executive Officer is also CODM. The CODM, together with other senior management personnel, focus their review on consolidated financial information and the allocation of resources based on operating results, including revenues and Segment Adjusted EBITDA, for each segment, separate from corporate operations. No operating segments have been aggregated to form the reportable segments.

Banks. ACI provides payment solutions to large and mid-size banks globally for retail banking, real time, digital, and other payment services. These solutions transform banks’ complex payment environments to speed time to market, reduce costs, and deliver a consistent experience to customers across channels while enabling them to prevent and rapidly react to fraudulent activity. In addition, they enable banks to meet the requirements of different real-time payments schemes and to quickly create differentiated products to meet consumer, business, and merchant demands.

Merchants. ACI’s support of merchants globally includes Tier 1 and Tier 2 merchants, online-only merchants and the payment service providers, independent selling organizations, value-added resellers, and acquirers who service them. These customers operate in a variety of verticals, including general merchandise, grocery, hospitality, dining, transportation, and others. The Company's solutions provide merchants with a secure, omni-channel payments platform that gives them independence from third-party payment providers. They also offer secure solutions to online-only merchants that provide consumers with a convenient and seamless way to shop.

Billers. Within the billers segment, ACI provides electronic bill presentment and payment (“EBPP”) services to companies operating in the consumer finance, insurance, healthcare, higher education, utility, government, and mortgage categories. The solutions enable these customers to support a wide range of payment options and provide a convenient consumer payments experience that drives consumer loyalty and increases revenue.

Revenue is attributed to the reportable segments based upon customer. Expenses are attributed to the reportable segments in one of three methods, (1) direct costs of the segment, (2) labor costs that can be attributed based upon time tracking for individual projects, or (3) costs that are allocated. Allocated costs are generally marketing and sales related activities.

Segment Adjusted EBITDA is the measure reported to the CODM for purposes of making decisions on allocating resources and assessing the performance of the Company’s segments, and therefore, Segment Adjusted EBITDA is presented in conformity with ASC 280, Segment Reporting. Segment Adjusted EBITDA is defined as earnings (loss) from operations before interest, income tax expense (benefit), depreciation and amortization (“EBITDA”) adjusted to exclude net other income (expense).

Corporate and unallocated expenses includes global facilities and information technology costs and long-term product roadmap expenses in addition to corporate overhead costs that are not allocated to reportable segments. The overhead costs relate to human resources, finance, legal, accounting, and merger and acquisition activity. These costs along with depreciation and amortization and stock-based compensation are not considered when management evaluates segment performance.