Stock-Based Compensation Plans - Schedule of Grant Date Fair Value Weighted Average Assumptions - TSRs (Details) - Total Shareholder Return Awards (TSRs) - Monte Carlo Simulation Valuation Model	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	2 years 3 months 18 days	2 years 8 months 12 days
Risk-free interest rate	4.00%	4.40%
Expected volatility	33.20%	36.80%
Expected dividend yield	0.00%	0.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

ACI WORLDWIDE, INC. 10-Q