The experimental drug CNTO 888 is currently being studied in cancer patients with solid tumors and this study is the first to use this drug for patients with idiopathic pulmonary fibrosis (IPF). This study tests the safety and effectiveness of CNTO 888 compared to placebo. The purpose of this research study is to determine if CNTO 888 is safe and to determine its effects (good and bad) on patients with IPF. The study will be conducted at approximately 28 sites globally. Patients can remain on usual, accepted treatment for IPF while enrolled in the study. Participating in other experimental studies or taking other experimental medications while participating in this study will not be allowed.