The efficient intense field double detachment of molecular anions observed in SF6- is studied by 3D coincidence imaging of the dissociation products. The dissociation anisotropy and kinetic energy release distributions are determined for the energetically lowest double detachment channel by virtue of disentangling the SF5+ + F fragmentation products. The observed nearly isotropic dissociation with respect to the linear laser polarization and surprisingly high kinetic energy release events suggest that the dissociation occurs on a highly excited state. Rydberg (SF6+)* states composed of a highly repulsive dication core and a Rydberg electron are proposed to explain the observed kinetic energy release, accounting also for the efficient production of all possible cationic fragments at equivalent laser intensities.