WASHINGTON — The Federal Communications Commission on Thursday released extensive details of how it would regulate broadband Internet providers as a public utility, producing official wording that almost certainly sets the stage for extended legal fights.

The release of the rules had been eagerly anticipated by advocates and lawmakers, as well as broadband and technology companies, since the agency approved new rules for Internet service two weeks ago. The details came in a 313-page document that included the new rules and the legal justifications for them.

The rules revealed how the strict laws would be modified for Internet providers, exempting the companies from the sort of price controls typically applied to utilities, for example. But the full text of the new order also raised uncertainties about broad and subjective regulation. One catchall provision, requiring “just and reasonable” conduct, allows the F.C.C. to decide what is acceptable on a case-by-case basis.

Opponents of the rules, including many of the leading Internet providers, spent Thursday poring over the document. It was not known who would file the first legal challenges, or exactly what legal arguments would be made. Many experts, though, said the document included plenty of opportunity for different interpretations.