Efficacy and Safety Study of Idelalisib in Participants With Indolent B-Cell Non-Hodgkin Lymphomas

Key Inclusion Criteria: * Karnofsky performance status of ≥ 60 (Eastern Cooperative Oncology Group \[ECOG\] performance score of 0, 1, or 2) * Histologically confirmed diagnosis of B-cell iNHL, with histological subtype limited to the following: * Follicular lymphoma (FL) * Small lymphocytic lymphoma (SLL) with absolute lymphocyte count \< 5 x 10\^9/L at the time of diagnosis and on baseline laboratory assessment performed within 4 weeks prior to the start of study drug administration * Lymphoplasmacytic lymphoma (LPL), with or without associated Waldenstroms Macroglobulinemia (WM) * Marginal zone lymphoma (MZL) (splenic, nodal, or extranodal) * Prior treatment with ≥ 2 prior chemotherapy-based or immunotherapy-based regimens for iNHL * Presence of radiographically measurable lymphadenopathy or extranodal lymphoid malignancy * Prior treatment with rituximab and with an alkylating agent (eg, bendamustine, cyclophosphamide, ifosfamide, chlorambucil, melphalan, busulfan, nitrosoureas) for iNHL * Lymphoma that is refractory to rituximab and to an alkylating agent * Discontinuation of all other therapies for treatment of iNHL ≥ 3 weeks before Visit 2 * For men and women of childbearing potential, willingness to abstain from sexual intercourse or employ an effective method of contraception during the study drug administration and follow-up periods * Willingness and ability to provide written informed consent and to comply with the protocol requirements Key Exclusion Crit…