A/R Aging reports
The A/R aging summary will have those groupings by customers and you can drill in from there. Check out “A/R Aging Summary Report” SuiteAnswers ID 7799. The A/R aging detail will have all the open invoices listed for all customers with their age. Check out “A/R Aging Detail Report” SuiteAnswers ID 7798. If you want something more specific in between those you’ll have to customize one of those or create your own report to get exactly what you want. Probably the A/R aging detail in your case, but depending on your use case you may be able to just export the standard detail report and use that.