By the late 1980s the idea had entered common usage.

"So far as I know, the idea never enters anyone's head."

The idea had simply never entered her head until one particularly bad night after Willie she'd found herself doing it without thinking.

At a certain point, ideas simply enter into the public consciousness.

Indeed, I am sure that such an idea will never enter their heads.

Too often ideas, whether political or cultural, enter the general consciousness through a movie director.

The idea that they might be afraid of different things never entered her mind.

And even as the idea entered his mind he knew that it was true.

Yet twenty-four hours earlier, such an idea could not even have entered his head.

Suddenly an idea entered his mind, which he thought might save him still.