The nuclear composition of primary ultra-high-energy cosmic rays (UHECRs) can be inferred from the observed distribution of depths of shower maximum (\(X_{\rm max}\)) of the induced extensive air showers. The observed Xmax distributions at various primary energies can be compared with the distributions predicted by detailed detector simulations for any assumed primary particle type and high-energy hadronic interaction model. In this paper, we present measurements of \(X_{\rm max}\) by the Telescope Array (TA) fluorescence detectors with stereoscopic shower reconstruction using 10 years of data. We find that for all hadronic models considered, the data collected is consistent with a chiefly light UHECR composition.