At the Iowa Republican caucuses on Monday night, Donald J. Trump secured a runaway victory. The only real drama was the fight for second place. Reid Epstein, who covers politics for The Times, takes us inside one of the caucuses, and Shane Goldmacher, a national political reporter, walks us through the final results. Guest: Reid J. Epstein, a politics correspondent for The New York Times, and Shane Goldmacher, a national political reporter for The New York Times.