Extract date from Excel file string

<cfscript>

filename="P_PAUL-QR-20180827183000.xls";

dateTimeString=listLast(listFirst(filename, "."), "-");

</cfscript>

The portion that you want is always 14 integers in length.  RegEx to the rescue. 

<cfset fileName = {however you are providing it} />
<cfset fnArray = REmatch("\d{14}",fileName) /><!--- returns an array of the matched values --->
<cfswitch expression="#arrayLen(fnArray)#">
    <cfcase value="1"><cfset datetime = fnArray[1] /></cfcase>
    <cfdefaultcase>Either there were zero datetimes, or more than one and I didn't know what to do.</cfdefaultcase>
</cfswitch>

HTH,

^ _ ^