Due to the abolished borders between the member states, EU nationals only need an identification document to travel throughout the Schengen Area.
On the other hand, foreign nationals will need to present several statutory documents when they show up at the Italy port of entry. Find these documents listed below:

• A valid passport or travel document. Valid for at least three more months beyond their planned date of Exit from Schengen and issued within the last ten years.
• A visa – if they are subject to the Italian visa regime.