Condensed Consolidated Financial Statements - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Amount of off balance sheet settlement funds	$ 216.2	$ 224.9

The balance of the settlement accounts at period end. Settlement accounts are trust accounts maintained for the benefit of the Company's clients. They are not included in the Company's balance sheet.

No definition available.

Name:	aciw_SettlementAccountsBalance
Namespace Prefix:	aciw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant