The phrase "alter the idea" is correct and usable in written English.
You can use it when discussing changes or modifications to a concept or thought.
Example: "After much discussion, we decided to alter the idea to better fit our target audience."
Alternatives: "modify the concept" or "change the notion."
The Real Thing, infused with a new emotion, altered the idea of this dramatist as being a primarily cerebral writer.
They've increasingly centralized and have radically altered the idea of the "web" for hundreds of millions around the globe.
In a time when poetry is either wrapped in this remote glamor, or entirely dismissed by far too many people, the Web has altered the idea of access to poetry in so many different ways.
As a side effect, Doll notes, the metamorphosis also alters the idea of incest into something natural for the imagination to think about.
The stage proved to be no mere handmaiden to evolutionary science, though, often resisting and altering the ideas at its core.
Matthew Boyd Goldie examines how natural philosophers, theologians, poets, and other thinkers in late medieval Britain altered the ideas about geographical space they inherited from the ancient world.
For Salvatore J. Cassano, the city's fire commissioner, the idea to alter the protocols first took root in the 1990s, when he was a division commander in Brooklyn and saw a civilian killed after a fire truck racing to a minor event crashed in the street.
Yes, we see how quickly a new idea can alter the course of a dance, but then what?
Senate President Pro Tempore Kevin B. Sullivan, a Democrat of West Hartford, called the proposal to alter the law "a politically motivated idea to embarrass the governor," and said, "we have better things to work on during the session than that".
The audacious idea, to alter the course of the Arno River in order to make Florence victorious in war and supreme in global commerce, brought together the elements of genius for which each of Mr. Masters's protagonists are known: Machiavelli's hard-headed, realistic political vision and Leonardo's startling prescience as an engineer.
