Interesting, I'm the opposite! I far prefer to start off with a bit of code to help explore gotchas I might not have thought about and to help solidify my thoughts and approach. It doesn't have to be complete, or even compile. Just enough to identify the tradeoffs of whatever I'm doing.

Once I have that, it's usually far easier to flesh out the details in the detailed design doc, or go back to the Product team and discuss conflicting or vague requirements, or opportunities for tweaks that could lead to more flexibility or whatever else. Then from there it's usually easier to get the rest of the team on the same page, as I feel I'll understand more concretely the tradeoffs that were made in the design and why.

(Not saying one approach is better than the other. I just find the difference interesting).