My potential employer want me to give up all my IP rights. Can they?

I have been an in house, full time 'contractor' for 3 years with a $50 million online Education company in Tucson. Their parent company is based out of Dallas. Realizing that they are abusing the contractor designation, they have offered me a position but have an overly broad IP clause in the contract they have asked me to sign. I have asked them to change the language but they have refused. I hold several patents in fields that may eventually overlap with the companies future endeavors. Here is the clause:

Article 5. Inventions/Intellectual Property 
All inventions, discoveries, and improvements that relate to the business of (the Company) which you conceive, develop, or reduce to practice during or after the period of your employment with (the Company) (collectively “Work Product”) are the sole property of (the Company). You will inform (the Company) of all inventions, discoveries, and improvements and will assign all right, title, and interest to them to (the Company). You will assign to (the Company) all interest in any patents, patent applications, or other intellectual property rights related to such inventions, discoveries, and improvements, and will assist (the Company) in obtaining, maintaining, and prosecuting such patents, patent applications, and intellectual property rights. If for any reason, any Work Product does not qualify as work made for hire, you will assign and do hereby assign to (the Company) all such Work Product (including, but not limited to, all patent rights, copyrights, and rights of authorship therein), free and clear of any liens, claims, or encumbrances. You will assist (at no personal financial expense) (the Company) in every necessary way to obtain or enforce any patents, copyrights, or any proprietary rights relating to the Work Product and to execute all documents necessary to give to (the Company) full legal ownership to such Work Product, and you agree to continue this assistance after the term of the Agreement. You have identified, in writing, all inventions which you made, conceived, or wrote, in whole or in part, and which relate to the actual or anticipated business or research or development at (the Company), if any. You represent that you are not a party to any agreement which would limit your ability to assign inventions as provided for in this Section. 

How can they ask for ownership of all my IP forever? This seems ludicrous.