A Great Deal Meaning

(idiomatic) Very much; to a great extent; a lot; lots.

Example:   We had a great deal more money afterwards.
  They had a great deal less than we had.
1904, John Henry Haaren, Famous Men of the Middle Ages: Gutenberg,
  While Gutenberg was growing up a new way of making books came into use, which was a great deal better than copying by hand.