This is a multicenter, phase 3, double-blind, randomized, placebo-controlled study. Patients who qualify for study inclusion will be randomized in a 1:1:1 manner to receive MGL-3196 100 mg, MGL-3196 80 mg, or matching placebo given orally once daily in the morning for up to 54 months. If any patient has a Composite clinical outcome event on the Week 52 liver biopsy or any clinical composite event after Week 52 and prior to month 54 they will discontinue from the main study and will be allowed to participate in an open-label study on active treatment with MGL-3196.