NEW YORK - Norman Mailer, the pugnacious prince of American letters who for decades reigned as the country's literary conscience and provocateur with such books as "The Naked and the Dead" and "The Executioner's Song," has died at the age of 84. Mailer died Saturday of acute renal failure at Mount Sinai Hospital, J. Michael Lennon, the author's literary executor and biographer, said. "He was a great American voice," said a tearful Joan Didion, author of "The Year of Magical Thinking" and other works, struggling for words upon learning of Mailer's death. From his classic debut novel to such masterworks...