Fourteen months after the Deepwater Horizon drilling rig exploded 50 miles southeast of Venice, La., killing 11 men and setting off the largest offshore oil spill in U.S. history, Transocean, the company that owned and ran the ill-fated 32,600-ton vessel, finally issued its official account of what happened and why. It produced a report on June 22 of no fewer than 854 pages, divided into two volumes, and spared no detail. The bottom line, though, isn’t complicated:It was BP’s fault.