LOS ANGELES -- The Los Angeles Dodgers on Friday made official the largest contract in baseball history for a pitcher -- the seven-year, $215 million deal for homegrown ace Clayton Kershaw -- but they say they may not be done adding to their star-studded rotation.

Dodgers general manager Ned Colletti said he has had talks with the agent for Japanese star Masahiro Tanaka nearly every day this week. Teams have until next Friday to reach a deal with Tanaka once they've agreed to pay his Japanese team its $20 million posting fee. Even with a payroll that is approaching $250 million for 2014, the Dodgers say they haven't necessarily reached the limits of their budget.

"We're still, first and foremost, concerned with the quality of the team we can put together, and adding it up comes second," team president Stan Kasten said. "This is a long-term strategy of ours. After five or six or seven years, it will make a lot more sense than it does to people looking at today's snapshot."

As hefty as Kershaw's deal was, it could have cost the Dodgers more. ESPN The Magazine's Buster Olney reported in October that the team had discussed what amounted to a lifetime deal in the $300 million range with their left-handed ace. By narrowing the terms of the deal, the Dodgers were able to make it more appealing to Kershaw, particularly when they agreed to a fifth-year out clause.

Kershaw, a two-time Cy Young winner who has led the majors in ERA for three straight seasons, could hit free agency in 2018 or '20, when he'll be 30 or 32.

Kershaw said he and his wife, Ellen, were looking for a seven-year deal all along.

"This is the longest amount of years I'm comfortable with committing myself to," Kershaw said. "I always want to be able to see the finish line and I think anything longer than this, I would feel overwhelmed trying to live up to those expectations and being able to pitch successfully for that long."

The Dodgers on Friday pointed to a confluence of factors that made them more comfortable committing so many dollars to a starting pitcher given the risks involved. They addressed Kershaw's charitable contributions, reasons behind him winning Roberto Clemente and Branch Rickey awards, as well as his work ethic and drive. They mentioned his age; he won't turn 26 until March. They also said they were able to get insurance to cover part of their losses if Kershaw is injured during the life of the contract.

"We know all the precedents, we know the risks," Kasten said. "A big part of this, for us, was getting as much protection from insurance as we could."

The Dodgers began talking to Kershaw about an extension last March, and there were reports going into the season that they were close to a deal similar to the one he signed this week. They said the talks were slowed by the distractions of the season and then by the Dodgers' need to shore up the rest of their team through free agency and trade talks. Finally, after Kershaw filed for arbitration Tuesday, the talks heated up.

Kershaw flew to Los Angeles on Tuesday for a physical. He did not attend Friday's media conference, instead calling in from his Dallas-area home. Kershaw, who would have reached free agency next November, said he never envisioned himself pitching for another team.

"I just kind of always had a feeling that it was going to work out and I didn't really let my mind get too much past it," Kershaw said.

The pitcher has founded and supported an orphanage in the African nation of Zambia as well as starting after-school programs for underprivileged kids in both Los Angeles and Dallas. He said he plans on extending his charitable efforts with the money from the new contract.

"Our heads have just been running with different things," Kershaw said.

Kershaw's contract is the richest deal for a pitcher in MLB history, eclipsing the seven-year, $180 million contract Detroit gave Justin Verlander last winter. Kershaw's average annual salary of $30.7 million is the highest ever for any baseball player.

Sources told Olney that because Kershaw agreed to an $18 million signing bonus, with just a $4 million salary for 2014, his salary for 2014 -- for salary arbitration purposes -- is at $6.57 million (calculated as $18 million divided by seven years and adding $4 million salary).

The Dodgers drafted Kershaw seventh overall in 2006, choosing the hard-throwing high-school lefty over future Cy Young Award winners Tim Lincecum (who went 10th overall to the Giants) and Max Scherzer (who went 11th overall to the Diamondbacks), both of whom were older, more developed college pitchers.