146c5814_What_is_an_Ideal_Op_Amp___Ideal_Op_Amp
[Characteristics] Positive and Negative Voltage Swings to Supply Rails [Real Op Amp] In real op amps, the amplified signal will not fully reach the DC supply rails. They will fall short of it. [Ideal Op Amp] 
In an ideal op amp, the ac voltage which is fed into the op amp to be amplified will swing all the way up for the DC positive supply rail and all the way down for the DC negative supply rail, making 100% efficient use of the DC voltage supplied to an op amp.
What is an Ideal Op Amp?
Ideal Op Amp