PASADENA, Calif. - CBS has hosts and starting dates for its remade late-night lineup - Stephen Colbert on Sept. 8 and James Corden on March 23 - and now is waiting to find out what kinds of shows the two men create.

The network announced Monday that Colbert will take over the "Late Show" after Labor Day. He's replacing David Letterman, who is retiring and will have his last show on May 20. CBS will air reruns of prime-time programming in the time slot until Colbert starts.

Colbert is bringing his creative team from "The Colbert Report" with him to CBS, and has said that he will no longer play the character of a blowhard political talk host that he perfected on the Comedy Central show.

"It will be nice to have the smartest guy in the room at 11:30," said Nina Tassler, CBS entertainment chairman, particularly with an election year coming.

That suggests Colbert may try to occupy a more topical niche than his comic competitors, Jimmy Fallon on NBC and Jimmy Kimmel on ABC. But Tassler said Colbert's "Late Show" is still in development and many of the details are still being decided.

"Whether or not he's going to start with an opening monologue, he's working on that right now," Tassler said. "But clearly he knows that he is introducing himself, the real Stephen Colbert, to his audience, and he's really putting a lot of attention on making sure that the show is still topical, is still relevant, still dealing with current events. That's really all he's said so far."

CBS is essentially waiting for Colbert to tell them what he has in mind.

"Part of the opportunity of being in business with a brilliant talent like Stephen Colbert is really letting him do what he wants to do," she said.

Tassler talked of being "mesmerized" by Corden when she and CBS Corp. chief executive Leslie Moonves first met with him. She described him as "a combination of Jack Black and Fred Astaire."

The British actor was a surprise choice to replace Craig Ferguson in the later night timeslot following Letterman. Although his debut is much sooner, Corden told reporters at a television conference on Monday that it's very much a work in progress. He said he and his creative team have only been on the job for a few days.

That left him short on details, although executive producer Rob Crabbe noted that since Corden has no background as a comedian, it might mean dispensing with the talk show staple of an opening monologue.

"We want to make a warm show that never feels spiky," Corden said. "So much of what you see and read and are polluted by is not pleasant right now. I'd like to remind people that there are still wonderful things going on."

Corden had warm praise for Letterman, Ferguson, Fallon and Seth Meyers - the latter two perhaps to CBS' chagrin. "I told Jimmy that (his) show is the very thing that inspires me and terrifies me at the same time," he said.

Since he didn't grow up watching American talk shows, Corden said he might be influenced by British talk show hosts like Graham Norton. But he doesn't expect his sensibility to lose something in translation: "Funny's funny and if it's good, it travels," he said.

For all the work that goes into developing the show, the important work will come after March 23.

"The truth is, we can prepare for the show for a year," he said. "It's only in the doing it that's going to tell us what is."