Unsolicited ideas will never be considered...as others have said, for legal reasons.
Years ago when my daughter was a fourth-year at Savannah College of Art and Design, she took a class that involved designing for Disney. She majored in Graphic Design, and this class took students from all design disciplines and all they knew when they signed up was that they would complete a design project and present to Disney. It was a wonderful 'real-life' opportunity, and she was lucky to get one of the spots in the class.
Once accepted, she had to first sign a multi-page non-disclosure agreement (NDA) that severely limited the ability to discuss the class with anyone (even us) and she had to agree to keep all phases of the class confidential. Work on the project couldn't be done in her dorm...had to be done in a specific studio and all materials kept there. Separate teams worked on the project Disney described to them, and then each team had to pitch their idea in a formal presentation as their final exam. Some, all, or none of their ideas would be accepted and actually used by Disney...and they all knew the possibility. Regardless of whether Disney used it, all the work and ideas belongs to Disney.
None of the work could be included in their portfolio, nor could it be shown to anyone, and no mention of the class participation could be included on their resumes for a period of five years from the conclusion of the class.
It was severely restrictive, but she still considers the class one of the best ones she took.