Those 'levers' you mention are the fuel control switches. They can be at 'idle' or at 'cut off'. In the former the engines are working, in the latter they are shut down. It has no bearing on idling as in producing idle thrust, do not get confused over this. Generally, engines in the cruise will produce sufficient thrust to maintain the desired speed, this will be significantly more than idle and less than maximum, but in rpm terms closer to the latter.