A Randomized Phase 2 Study of Atezolizumab (an Engineered Anti-PDL1 Antibody) Compared With Docetaxel in Participants With Locally Advanced or Metastatic Non-Small Cell Lung Cancer Who Have Failed Platinum Therapy - "POPLAR"

Inclusion Criteria: * Adult participants, \>/= 18 years of age * Locally advanced or metastatic (Stage IIIB, Stage IV, or recurrent) non-small cell lung cancer (NSCLC) * Representative formalin-fixed paraffin-embedded (FFPE) tumor specimens * Disease progression during or following treatment with a prior platinum-containing regimen for locally advanced, unresectable/inoperable or metastatic NSCLC or disease recurrence within 6 months of treatment with a platinum-based adjuvant/neoadjuvant regimen * Measurable disease, as defined by RECIST v1.1 * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 Exclusion Criteria: * Known active or untreated central nervous system (CNS) metastases as determined by CT or MRI evaluation during screening and prior radiographic assessments * Malignancies other than NSCLC within 5 years prior to randomization, with the exception of those with a negligible risk of metastasis or death and treated with expected curative outcome * History of autoimmune disease * History of idiopathic pulmonary fibrosis (including pneumonitis), drug-induced pneumonitis, organizing pneumonia, or evidence of active pneumonitis on screening chest CT scan. History of radiation pneumonitis in the radiation field (fibrosis) is permitted. * Active hepatitis B or hepatitis C * Prior treatment with docetaxel * Prior treatment with CD137 agonists, anti-CTLA4, anti-PD-1, or anti-PD-L1 therapeutic antibody or pathway-targeting agents