Legolas and the Balrog

[doug*platypus]

In the Books, as opposed to the Movie, the existence of a Balrog at Moria appears to have been completely unrealized by anyone, with the likely exception of Galadriel.

That brings up a good point, MOTW (thanks for your post, by the way, I enjoyed reading it!). Didn't the dwarves know for sure that Durin's Bane was a Balrog? It killed Durin, Náin (I think), and probably quite a few other dwarves.

Gandalf, Aragorn, Legolas and Gimli all should have been aware of its presence in Moria, right? Or were the dwarves always unaware of what exactly was lurking in the depths? If members of the Fellowship did know that a Balrog was at large in Moria, was it not just a little too risky taking the Ringbearer through there? What about the mountain pass that Bilbo and the Dwarves used previously?