Lenalidomide and Idelalisib in Treating Patients With Recurrent Follicular Lymphoma

* Documentation of Disease * Previously treated, histologically confirmed follicle center cell lymphoma, World Health Organization (WHO) classification grade 1, 2, or 3a (\> 15 centroblasts per high-power field with centrocytes present) * Bone marrow biopsies as the sole means of diagnosis are not acceptable; fine-needle aspirates are not acceptable for diagnosis * Confirmed Cluster of Differentiation 20 (CD20) antigen expression by flow cytometry or immunohistochemistry * Measurable disease must be \> 1 cm * Prior treatment * Patient must have had prior treatment with rituximab either alone or in combination with chemotherapy. * Last prior treatment regimen need not include rituximab. * Patient must have a time to progression of ≥ 6 months from last rituximab dose of last rituximab containing regimen. * No corticosteroids within two weeks prior to study, except for maintenance therapy for a non-malignant disease; maintenance therapy dose may not exceed 20 mg/day prednisone or equivalent * Patients must be 18 years of age or older. * Human immunodeficiency virus (HIV) Infection * Patients with HIV infection are eligible, provided they meet the following: * CD4+ cell count \> 350/mm\^3 * Treatment sensitive HIV and, if on anti-HIV therapy, HIV viral load \< 50 copies/mm\^3 * No history of Acquired Immunodeficiency Syndrome (AIDS)-defining conditions or other HIV related illness * No concurrent zidovudine or stavudine because of overlapping toxicities…