So far there are 2 somewhat standards.
Classic USB is 500mA and is not enough to get a fast charge or power some devices. To work around this the industry put out a 2000 mA (or 2A) charger and all that is well discussed.
I would be guessing why you don't have this charger. Maybe the camera only came with the cord or the charger was lost.
But I see you found the same lack of detail I did.