Flying in Russia requires an air ticket containing the treaty provisions on aviatransportation and passport (or other document proving the identity).
You can learn about the requirements to different kinds of documents needed to fly abroad, from your agent selling you the ticket containing the treaty provisions on aviatransportation. However, this will be only a reference, while the official information is available at the Consulate of your destination country.
A passenger should follow all the laws, regulations, rules and prescriptions of the government organs of any country to, from or through whose territory they are travelling, as to passport, customs, sanitary, currency, quarantine, and other procedures.
When starting your journey, don’t forget to take your passport, a valid visa and other documents necessary to enter the country.