At my previous bank we obtained conductor info on cash transactions of $5,000 or more; this was in place for quite a few years. At my current bank (which is much, much smaller) we stick with the $10,000 threshold.
When asked about the need for the ID, our tellers usually stated that it was bank policy (at the previous bank). Here we offer the pamphlet.
My opinions do not necessarily reflect those of my employer.