Gaia will often appear as "idle" in your Task Manager, but it's not running and hence not consuming CPU/battery. Any service with state "idle" means that it has completed its lifecycle, but Android has not offloaded it from its "app/service history list".
Gaia GPS will usually appear in a Task Manager because its map download service works in the background. So, on start-up or when the network state changes, Gaia will check for downloads, and then go idle and do nothing if there are no maps to download.
This service is activated on 3 events:
- When user explicitly start/resume new map download
- When the phone boots (checks for downloads to resume)
- When network state changes - edge/3G/4G/wifi connect/disconnect (checks for downloads to resume)