From CSNNE.com who broke the news:
Doc Rivers has agreed on a five-year contract extension with the Celtics, according to a team source with knowledge of the negotiations.
Terms were not disclosed. The final details of the agreement are still being worked upon.
Greg Dickerson also tweeted it.
Update with salary figures: Twitter / @Adrian Wojnarowski: .
Doc Rivers' new contract with the Boston Celtics will pay him $35 million over the 5 years, sources tell Y! Sports.