You own the copyright to your thesis/dissertation, however, this does not extend to the data, software, algorithms or intellectual property (inventions, methods, processes, designs) used or described in your thesis research. The University also retains ownership of laboratory notebooks and original records of research. 
Publishing through ProQuest or depositing through IDEALS does not affect your ownership of your dissertation. The agreement with ProQuest is non-exclusive, giving you the right to re-publish your work elsewhere. For more information, read about depositing your dissertation in IDEALS.