Quarterback Carson Palmer will retire after 15 NFL seasons, he announced in a goodbye letter on Tuesday. The announcement comes one day after his coach with the Arizona Cardinals, Bruce Arians, announced he would be leaving the team and retiring to seek other opportunities.

Palmer, who turned 38 last week, was the first overall pick of the Cincinnati Bengals in 2003. He played seven seasons there, followed by two with the Oakland Raiders and five more to close out his career in Arizona.

"Over the years, I’ve had teammates who decided to hang it up and I would ask them how they knew when it was time to walk away," Palmer wrote. "The answer was almost always the same: You just know.

"For me that time is now. Why? Quite simply, I just know."

The MVP runner-up in 2015, Palmer helped the Cardinals reach the NFC title game that season. But he never was able to regain that form, taking a step back last season and suffering a season-ending injury in the Cardinals' 33-0 loss in London this season to the Los Angeles Rams.

Palmer's career was defined by a slew of injuries, including shoulder problems and multiple torn ACLs. He suffered a broken arm in the loss to the Rams.

The next big retirement decision in Arizona will be that of Larry Fitzgerald, who has said he will take some time to make that announcement.

Palmer will hit on the Cardinals' 2018 salary cap for about $6.6 million, but retiring will still save the team $14 million against it. The Cardinals currently do not have any quarterbacks under contract for 2018. Drew Stanton, Blaine Gabbert and Matt Barkley all are due to become free agents.

A three-time Pro Bowler, Palmer will leave the game ranked 12th all time in passing yards with 46,247 and 12th in career TD passes with 294.