Inventors and their ideas are as American as baseball and apple pie.
Typical inventions are physical objects, procedures, methods, and products.
There are many types of inventions. For an idea to be termed an invention, an inventor must conceive of an idea and then reduce it to practice. In other words, you must be capable of explaining how the idea will be reproducibly applied in a real world example. But if the inventor actually knows how to build such a machine, he has a great invention. An idea needs to be more than just abstract to be an invention.