The time dependent density functional theory (TDDFT)-Floquet formalism studied was applied to multiphoton and above threshold detachment of Li^- negative ion. The exterior-complex-scaling-generalized-pseudospectral (ECSGPS) method was extended to the nonperturbative calculations of complex-quasienergy resonances of many-electron quantum systems. The transformations of the angular distributions in the vicinity of the two-photon threshold were observed and analyzed.