It may be a regionalism, but many speakers say or write ideal when they mean idea. For example:
I have an ideal for next year’s Christmas: Move the date.
Comic Silverman has an ideal for ending world hunger: Sell the Vatican.
Do you have any ideals for how I can ease my fear of flying?
The noun idea can be used with philosophical connotations, but as the word is used in ordinary conversation, it usually means “the picture or notion of something formed in the mind.” Here are some correct uses of idea:
I have an idea for next year’s Christmas: Move the date.
Comic Silverman has an idea for ending world hunger: Sell the Vatican.
Do you have any ideas for how I can ease my fear of flying?
I have an idea; let’s go to the movies.
An inventor begins with an idea of the thing to be made.
He wants to visit Paris, but the idea of flying makes him hesitate.
As a noun, ideal means “a person or thing regarded as a perfect example or representative”:
James Garner was the ideal of a Hollywood leading man with thick black hair, square jaw, perfect teeth, and a charming smile.
The Grace Project: Transforming Our Ideal of Female Beauty
The noun ideal is also an antonym of real used as an abstract noun:
In politics as in personal matters, individuals must come to terms with the disparity between the ideal and the real.
The notion of an ideal, of something, which for whatever reason, ought to be, as distinguished from what is. –J. Grote
Ideal used as an adjective does not attract the misuse that haunts ideal as a noun. In the following examples ideal means, “regarded as perfect or supremely excellent in its kind”:
Bond girl Bérénice Marlohe talks about her ideal man
What’s the ideal breed for a family dog?
In an ideal world, prime ministers would indeed put great thought and effort into establishing a highly skilled, intellectually impressive, thoughtful and engaged Senate. But it’s not an ideal world.
Ideal can also mean “existing only in idea; not real, actual, or practical”:
Administrators must compromise between practical and ideal solutions.