If my MacBook got stolen. Am I able to get my documents from that computer put on a new one?

In addition to babowa's answer regarding a Time Machine backup, if you stored your documents in iCloud they will be retrievable from iCloud.

Introduction to iCloud - Apple Support

Back up your files with Time Machine on Mac - Apple Support

Only you can know how you chose to store your documents and other files.

You'd have to maintain a current backup which you can then use to transfer those files to your new one. Without a backup: no.