Here is the how to set up AWS Detailed Billing Reports so that Cost Insights and Cloud Billing Manager functions as expected.
To turn on detailed billing reports:
1. Sign in to the AWS Management Console using the Payer (Reseller) account and open the Billing and Cost Management console at https://console.aws.amazon.com/billing/home#/.
2. On the navigation pane, choose Preferences.
3. Select the Receive Billing Reports check box.
4. Designate the Amazon S3 bucket where you want AWS to publish your detailed billing reports.
5. After your S3 bucket has been verified, under Report, select the check boxes for the reports that you want to receive. You need to select required reports: Monthly report and Detailed billing report with resources and tags, but we recommend selecting ALL of the reports:
6. Choose Save preferences.
Now, got to Settings -> Customers, Edit the specified customer and cloud account, and add Bucket Name as seen in screenshot
Note: It can take up to 24 hours for AWS to start delivering reports to your S3 bucket. After delivery starts, AWS updates the detailed report files multiple times per day.