The Phillies will no longer wonder the fate of Roy Halladay. The former ace retired on Monday afternoon after signing a one-day contract to retire as a Blue Jay, having spent 12 years of his career with Toronto.

Jon Heyman of CBSSports.com first reported the news.

"As much fun as I had in Toronto, Philadelphia was kind of the icing on the cake for me," Halladay said at his retirement press conference.

"I'd love to retire with two teams," he said. "Really, I felt like I want the Phillies to know, I want the fans to know, how much I enjoyed my time there. I've played in two places where the fans are extremely supportive. They may boo you on the field, but they're the first ones to come up to you on the street and smile and shake your hand and greet you."

The 36-year-old also said he had so many people to thank that "to sit down and name everyone of them would be virtually impossible."

"I was very fortunate to have a lot of people who backed me, supported me, through the bad times and the good times," he said.

Halladay also sent a special thank you to his family, who he said "were a big part of why I'm here."

His career ends with a 203-105 record, a 3.38 ERA, and 2117 strikeouts. Since debuting with Toronto in 1998, Halladay has thrown 2,749.1 innings, leading the league in innings pitched four times. Halladay threw 67 completes games (leading the league seven times) and 20 shutouts (leading the league four times).

Injuries surfaced in the latter part of his career, starting in 2012 with a shoulder strain, leading to his first significant time on the disabled list since 2009. Halladay still finished with an 11-8 record and recorded his 2,000th strikeout, but the following season he was sidelined by surgery to remove a bone spur.

The wear and tear on his body played a factor in his decision to retire. Halladay said his shoulder was not the main problem, though, and that his back was the real issue.

"The biggest thing is I'm trying to avoid surgery. I feel like it's the right decision for us," Halladay said. "We'll improve quality of life and give me a chance to hopefully not ruin my kids."

"If my career is shorter because I wanted to be out there two or three more innings, I'm okay with that. As long as I didn't feel like I was hurting our chances, I was ready to go. You want to take every chance you have, every second you have, to continue to pitch."

Despite making the playoffs with the Phillies, Halladay's World Series ring eluded him. "When the squirrel runs across home plate when your team is trying to pitch... you realize some things are out of your control," he said, referring to the 2011 NLDS.

The Cy Young winner said he plans to stay active, and even joked about trying to find a 35+ basketball league.

"I wanted to leave baseball better than when I found it. I tried to do things the right way. I tried to do that to the best of my ability," he said. "And not just pitching, about playing the game the right way, being respectful to your teammates. Hopefully, that's something I can pass on."

Halladay is an eight-time All Star and won the American League Cy Young in 2003 and the National League Cy Young in 2010. In 2010, he pitched a perfect game against the Marlins and, in the first round of the playoffs against the Reds, threw the second no-hitter in MLB playoff history.

"I've always wanted to win a World Series," Halladay said, "and hopefully down the road I can be a part of that in a different aspect."