On February 1st, 2016, Microsoft Azure DocumentDB bill be transitioning away from a Global Pricing Meter to be on Regional Pricing Meters instead. With Global Pricing charges are based on the country or region associated with the Azure Subscription. After the change to Regional Pricing Meters, charges will be based on the Azure Region in which your data resides. This change may possibly result in a price increase in your DocumentDB usage on your monthly bill.
Azure DocumentDB is a NoSQL document database that uses the JSON data format for storing and querying documents. Being a feature of Microsoft Azure, DocumentDB offers a nice NoSQL database using JSON documents that includes all of the benefits of Microsoft Azure and the cloud.
For more Azure DocumentDB billing information, please see the official DocumentDB Pricing page.