Only days before the Deepwater Horizon oil rig exploded, BP chose to use material for its well that a company document warned was less safe than alternatives, The New York Times reports. According to the document, BP was concerned that a method they used to seal the oil well only provided one barrier to leaking gases—the likely cause of the explosion—versus two for an alternate method. In the end, they went for the "best economic case" as the document put it. BP says their approach wasn't unusual for the industry. Meanwhile, efforts to plug the leak using BP's "top kill" method are under way and the company's CEO has predicted 60 to 70 percent odds of success.