What's the name of this doctrine and (when) did the Eastern Orthodox Church condemn it?

"God is merciful and He wants all people to be saved, thus, all the humans, even the worst ones, having fully redeemed themselves from their wrongdoings by spending some adequate time in the hell, will finally make it to the paradise..." What's the official name of this doctrine? I heard something like "optimistic eschatology", but I am not sure. And also, I heard that the Eastern Orthodox Church has condemned this doctrine as a heresy. If it's true, when and where (on which counsel) did this take place?