This global, multicenter, open-label, randomized, controlled study will evaluate the efficacy and safety of atezolizumab (an anti-programmed death−ligand 1 [anti-PD-L1] antibody)compared with docetaxel in participants with locally advanced or metastatic non-small cell lung cancer (NSCLC) after failure with platinum-containing chemotherapy. Participants will be randomized 1:1 to receive either docetaxel or atezolizumab. Treatment may continue as long as participants are experiencing clinical benefit as assessed by the investigator, i.e., in the absence of unacceptable toxicity or symptomatic deterioration attributed to disease progression.