The Cardinals' offseason of change won't be limited to their head coaching position. They'll also need a new quarterback.

Carson Palmer announced his retirement Tuesday.

"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. The answer was almost always the same: You just know," Palmer wrote. "For me that time is now. Why? Quite simply, I just know."

You can read the rest of his letter below:

Palmer, 38, entered the NFL as the No. 1 overall pick in the 2003 draft. He spent the first portion of his career with the Bengals, leading them to their first playoff game in 15 years in 2005. But tragedy struck in their opening game of the postseason when Palmer tore his ACL against the Steelers. He never was the same quarterback in Cincinnati. Eventually, he requested a trade. When the Bengals didn't trade him, he retired only to un-retire after the Bengals finally met his demands.

He wound up in Oakland, where he quarterbacked the Raiders from 2011-12 before he was traded once again. This time, he landed in Arizona, where he experienced a career renaissance. From 2013-17, Palmer threw for 105 touchdowns and posted a 91.1 passer rating. He nearly won MVP in 2015 and fell a game short of leading the Cardinals to the Super Bowl. 

Palmer retires with 46,247 career passing yards, 294 touchdown passes, 187 interceptions, and an 87.9 passer rating. His underrated career will likely be remembered for all of the what-ifs. If bad injury luck hadn't bitten him throughout his career, he might've been retiring with a Super Bowl ring. 

The Cardinals already lost coach Bruce Arians to retirement this week. Now, they're losing their franchise quarterback. Future Hall of Fame receiver Larry Fitzgerald could be next. Fitzgerald, 34, hasn't determined if he'll return for the 2018 season even though he signed a one-year extension in November. 

In April 2016, Fitzgerald said that his future was likely tied to Palmer's.

"A lot of it's tied to Carson [Palmer] -- Carson's playing at a high level," he said at the time, via "I don't want to go through any other quarterback situations. It's been great to have the stability that we have now with the big fella, he's been playing light's out."

The Cardinals don't really have another quarterback option on their roster. Both Drew Stanton and Blaine Gabbert have repeatedly proven they're not good enough to be the team's starter moving forward. The Cardinals might try to find their quarterback of the future in the draft, but they're not scheduled to pick until No. 15. Or maybe they'll chase a free agent like Drew Brees, Kirk Cousins or Sam Bradford. As ESPN's Josh Weinfuss pointed out, Palmer's retirement frees up $14 million in cap space.

Strangely enough, just minutes after Palmer announced his retirement, the Bengals announced that they're retaining Palmer's former coach, Marvin Lewis. Somehow, despite never winning a playoff game, Lewis has outlasted Palmer's NFL career.