Basis of Presentation	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals, considered necessary for a fair presentation have been included. Certain amounts in prior-period financial statements have been reclassified to conform to the current period’s presentation. Such reclassifications have no effect on previously reported net income or shareholders’ equity. For further information, refer to the audited consolidated financial statements and related footnotes included in Cass Information System, Inc.’s (the “Company” or “Cass”) Annual Report on Form 10-K for the year ended December 31, 2022.