Can a California Employer Claim Employee Copyrights?

If Franz Kafka had an overreaching copyright provision in his
employment agreement, his insurance company employer
might have owned the rights to "The Trial." 

Dear Rich: As a condition of working for a large company, I am required to agree to an Intellectual Property and Confidentiality Agreement. The only mention of copyright is in the section with "all copyrights in works authored by me ... during the term of this Agreement are and shall be the exclusive property of the Employer." Unlike Work Product or Inventions, there are no qualifiers on copyrights, such as that the works have to be related to the business of the employer, done as part of working for them, etc. It seems to me that this means that a hypothetical, say, an automotive company would then own the copyright to anything I write on the weekends, even if completely unrelated to the company such as a fiction novel I write about a dog with superpowers. Is there anything in the (specifically California) law that protects copyrights against this very broad-reaching clause?
We doubt that a California judge would permit an employer to own an employee's superpowered dog novel. Here's why:
Public policy. A contractual provision won't be enforced if the provision violates public policy (public policy is the moral and ethical principles upon which the legal system is created). Your provision appears to violate California's public policy which aims to protect employees from overreaching employers as evidenced by (1) a California labor statute that prevents employers from claiming non-work related inventions (innovations that don't involve employer time or resources), and (2) a law that prohibits non-compete agreements. The public policy behind federal copyright law supports an employee's right to own works unless created within the course of employment.
Unconscionability. A contractual provision also won't be enforced if the provision is unconscionable (grossly unfair). What if the Superdog novel is published, attracts a movie deal and becomes a blockbuster with sequels? Your agreement might be considered to be unconscionable because your payment (your paycheck) is so disproportionate in value as to demonstrate bad faith (or “unconscionability”) in the bargaining process.