MOSFETs Gate Driver: Current drawn from the Power Supply
The supply current when not driving MOSFET gates will be negligible compared to when the MOSFETs are attached. That is why it doesn't appear to be specified in the data sheet. So, if you want a realistic value for current calculate the average current waveform into the gate source capacitance and bear in mind that each MOSFET gets charged and discharged every switching cycle.

As an example, if the gate-source capacitance is 2 nF and the driving voltage is 15 volts then an energy of 2 nF * 225 / 2 joules is required for each MOSFET each cycle. That's a total MOSFET gate energy of 450 nJ and, if this is operating at 100 kHz, that's an average power of 45 mW. Given that the power taken from the supply is going to be more than double this value you can estimate 100 mW just to drive the gates.

From a 15 volt supply that is about 7 mA.

Add-on a few extra mA for internal consumption and you are in the 10 mA region. Clearly if the MOSFET gates are higher capacitance (can be 10 nF or more), the overall consumption will rise towards 40 mA.