The conventional Gaussian detector based on the sample mean has been widely used in amplify-and-forward (AF) relaying by considering the Gaussian noise only. In a practical wireless network, co-channel interference may exist due to multiple access or frequency reuse. Such interference often follows a symmetric alpha stable (SαS) distribution that may not have a finite mean. As a result, the conventional Gaussian detector performs very poorly when both impulsive interference and Gaussian noise are considered. In this paper, novel suboptimum detectors for signals corrupted by SαS interference and Gaussian noise are proposed for AF relaying. Numerical results are presented to show that the new suboptimum detectors have performance gains on the order of tens of decibels in effective signal-to-noise ratio (SNR) over the conventional Gaussian detector under the same conditions.