The objectives of this study are to assess the safety and efficacy of treatment with pirfenidone 2403 milligrams per day (mg/d) compared with placebo in patients with idiopathic pulmonary fibrosis (IPF), to assess the safety and efficacy of treatment with pirfenidone 1197 mg/d in patients with idiopathic pulmonary fibrosis and to characterize the pharmacokinetic disposition of pirfenidone in patients with idiopathic pulmonary fibrosis.