You might get a stronger indication if you have the headlights on. This will pull down the battery more if the alternator is malfunctioning, making the indication easier to see because of the lower voltage.
If you still have the described voltage (14.4 ?) with the headlights on at idle, it may not be the alternator.
Typical failure mode is a diode going bad inside the unit, resulting in a lower charging voltage because less AC is getting rectified into DC. Could be the regulator too. Since these components are probably all inside your alternator, the typical problem resolution is to replace the entire unit.
However, even with a bad alternator I would think the lights might dim (and flicker some) but should not go completely out.
Another potential fix is to clean the alternator electrical connections - not too likely the problem but a cheap potential fix.