This tutorial will detail how to enable offline mode for Google Docs

Navigate to Google Drive and click on the gear icon

Next click on settings

On the settings page there is a option for Offline. Please click the Check Box to enable the Google Drive Suite to work Offline.

With this setting enabled everything you do within the Google Drive Suite will be stored locally on the device

The next time the device is connected to a WiFi network it will sync all work done offline with Google Drive