The contract reportedly includes a $5.2 million signing bonus and $10.25 million in guaranteed money.
Cox, 26, spent his first four NFL seasons with the Jacksonville Jaguars, proving himself to be an above-average starter. His biggest issue has been health: He has missed 17 games over the past three seasons.
Last season, Cox finished with four interceptions and permitted just one touchdown pass. Quarterbacks had a passer rating of 44.5 against him, the lowest figure among all NFL cornerbacks, according to Pro Football Focus.