We formulate two intrusion detection system (IDS) design problems for smart grids. The first one optimally places IDS devices on communication paths, while the second one addresses the resilient communications requirement and enhances the first problem with the provisioning of K distinct back-up paths and additional IDS devices. The developed problems harmonize real-time communication requirements with the infrastructure's resource limitations (e.g., bandwidth), detection requirements, and the available budget. A heuristic approach is developed based on the column-generation model to reduce the computation time. Experimental results comprising the Romanian 440 kV and 220 kV power transmission networks, the Romanian Educational Communication Network, alongside synthetic topologies demonstrate the effectiveness and applicability of the heuristic methodology on large problem instances.