Conversation so far:
When did Walter Cronkite get started at CBS News?
In 1950, Cronkite joined CBS News.
How did Walter Cronkite get the job at CBS News?
He received a job offer from Edward R. Murrow at CBS News to join the Murrow Boys, relieving Bill Downs as the head of the Moscow bureau.

Question: How long did he stay there?
Self-contained rewrite: How long did Walter Cronkite stay at CBS News?