Enterprise customers that have an enterprise agreement can utilize https://ea.azure.com to download their usage and billing reports. Also, a new Power BI content pack was released recently that can be utilized to view Azure usage and costs through reports and a dashboard in Power BI.
More information about Enterprise agreements usage and costs is available at https://azure.microsoft.com/en-us/blog/new-power-bi-content-pack-for-azure-enterprise-users/.