Inclusion Criteria:

          -  Male or female Japanese participant who must be ≥ 18 years of age

          -  Histologically confirmed, relapsed or refractory, FL Grade 1, 2, and 3a

          -  Ineligible for HSCT

          -  Must have been treated with at least 2 prior systemic therapies for FL

          -  ECOG performance status 0 to 2

          -  Life expectancy ≥ 12 weeks

          -  Female participants agree to use medically acceptable contraceptive measures, should
             not be breastfeeding, and must have a negative pregnancy test before the start of
             study drug administration.

          -  Female participants of childbearing potential must understand and accept that
             pregnancy must be avoided during participation in the study.

          -  Male participants should avoid fathering children from screening through at least 90
             days after the last dose of study treatment.

        Exclusion Criteria:

          -  Known histological transformation from indolent NHL to DLBCL

          -  History of central nervous system lymphoma (either primary or metastatic)

          -  Prior treatment with the following:

               1. Selective PI3Kδ or pan-PI3K inhibitors (eg, idelalisib, copanlisib, duvelisib,
                  etc).

               2. Bruton's tyrosine kinase inhibitor (eg, ibrutinib).

          -  Allogeneic SCT within the last 6 months, or autologous SCT within the last 3 months
             before the date of study treatment administration

          -  Active graft-versus-host disease

          -  Use of immunosuppressive therapy within 28 days of the date of study treatment
             administration

          -  Concurrent anticancer therapy

          -  Significant concurrent, uncontrolled medical condition including, but not limited to,
             renal, hepatic, hematological, gastrointestinal, endocrine, pulmonary, neurological,
             cerebral, or psychiatric disease

          -  Current or previous other malignancy within 3 years of study entry, except cured basal
             or squamous cell skin cancer, superficial bladder cancer, prostate intraepithelial
             neoplasm, carcinoma in situ of the cervix, or other noninvasive or indolent malignancy
             without sponsor approval.

          -  Hepatitis B (HBV) or HCV infection

          -  Current New York Heart Association Class II to IV congestive heart failure or
             uncontrolled arrhythmia