CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - UNAUDITED (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Statement of Cash Flows [Abstract]
Cash and settlement assets acquired	$ 0	$ 46,432

The cash and restricted cash/settlement assets associated with the acquisition of a business during the period.

No definition available.

Name:	csgs_CashAndRestrictedCashAcquiredFromAcquisition
Namespace Prefix:	csgs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration