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 with protocol therapy * Patients must not have known central nervous system (CNS) involvement * Patients must not have known positivity for hepatitis B, as evidenced by + HBsAG or anti-HBc and must not have known history of hepatitis C * Patients must not have any currently active secondary malignancy except non-melanoma skin cancer. Patients are not considered to have a "currently active" secondary malignancy if they have completed anticancer therapy and are deemed to have \< 30% risk of relapse by their physician. * Patients must not have had deep vein thrombosis or pulmonary embolism within the past 3 months. * Patients must not have had radioimmunotherapy within 12 months of study entry. * Patients must not have other concurrent investigational or commercial agents or therapies for lymphoma. * Patients must not have current dialysis treatment. * Patients must be non-pregnant and non-nursing. * Females of Child Bearing Potential (FCBP) is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy or 2) has not been naturally postmenopausal for at least 24 consecutive months (eg, has had menses at any time preceding 24 consecutive months) * FCBP must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10-14 days prior to registration * FCBP must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control * One highly effective method and one additional effective method AT THE SAME TIME, at least 28 days before starting lenalidomide * FCBP must also agree to ongoing pregnancy testing * Men must agree to use a latex condom during sexual contact with a female of childbearing potential, even if they have had a successful vasectomy * CYP3A4 Strong Inducers and Inhibitors * Patients must not be on strong CYP3A4 inhibitors and/or inducers. * Strong inhibitors are prohibited: indinavir, nelfinavir, ritonavir, clarithromycin, itraconazole, ketoconazole, nefazodone * Strong inducers are prohibited: carbamazepine, phenobarbital, phenytoin, pioglitazone, rifabutin, rifampin, St. John's Wort, troglitazone * Required Initial Laboratory Values * Absolute neutrophil count (ANC) ≥ 1,000 mm³ * Total Bilirubin ≤ 2 times upper limit of normal (ULN) (unless due to Gilbert disease or lymphoma) * Creatinine ≤ 1.5 times ULN (unless due to lymphoma) OR creatinine clearance (CrCl) ≤ 60 mL/minute * Platelet count ≥ 75,000 mm³ * Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) ≤ 2 x ULN