How much detail does one include in a complaint?
See the procedural law your jurisdiction and how courts apply it. You only mention that you suing in the US, but not the state or even whether your complaint is to be filed in federal or state court. The applicable "court rules" or "rules of civil procedure" of your jurisdiction provide guidance on how much detail pleadings are expected to include.
Also make sure you read case law such as Ashcroft v. Iqbal, 129 S.Ct. 1937, 1949 (2009) and the cases cited therein. For instance, "the pleading standard [...] does not require detailed factual allegations, but it demands more than an unadorned, the-defendant-unlawfully-harmed-me accusation [...] A pleading that offers "labels and conclusions" or "a formulaic recitation of the elements of a cause of action will not do. [...] Nor does a complaint suffice if it tenders naked assertion[s] devoid of "further factual enhancement" (citations and internal quotation marks omitted).
It is usually difficult for litigant with no prior experience and no background in law to discern what is relevant or even what are the prima facie elements (or defenses) that ought to be established. That is why doing legal research prior to filing one's pleadings is strongly encouraged. Unfortunately many pro se litigants (including me) are unaware of the importance of doing enough preparatory work when we file our first complaint.
but just read (on avvo) that providing too much detail can get the suit dismissed.
That in and of itself is not a sound statement. Did that person elaborate or provide any sources for that assertion? Typically there is some amount of litigation before a court dismisses a case. During that litigation the plaintiff has the opportunity to amend the complaint or posit how the pleadings are clear enough for ascertaining the merits of a claim.