Quin was released by the Lions on Friday, Dave Birkett of the Detroit Free Press reports.
The 33-year-old started all 96 games in his six seasons with Detroit, averaging 71 tackles and 3.2 interceptions per year. He was one of the better free safeties in the NFL during his prime, but the Lions would rather clear out $6.25 million in cap space at this stage of Quin's career. The veteran shouldn't have too much trouble finding a chance to compete for another starting job, while Tracy Walker is poised to take over as the top free safety in Detroit.