An idle mode load balancing capability enables balancing of idle mode wireless devices across wireless carriers in order to ensure that the possibility of congestion on any given wireless carrier is reduced or even minimized when idle mode wireless devices become active. The idle mode load balancing may be performed for wireless carriers by determining relative numbers of idle mode wireless devices on the wireless carriers and performing idle mode load balancing for the wireless carriers based on the relative numbers of idle mode wireless devices on the wireless carriers. The relative number of idle mode wireless devices on a wireless carrier may be determined based on a change in load on the wireless carrier during the observation period, which may be determined based on an observed change in load on the wireless carrier and a load correction associated with session terminations on the wireless carrier.