Unsupervised Classification for documents
If you have a good amount of instances for every class, you can try using a density-based approach for clustering, with algorithms like DBSCAN.

If you can label at least some of the documents, you can use semi-supervised learning. Usually, when SSL is used for clustering, you need to specify "cannot link" and "must link" constraints for some pairs of instances, which is basically labeling some instances. One algorithm that follows this approach is HMRF-KMeans (Hidden Markov Random Fields K-Means).