Cablevision, the cable operator that has until now focused its attention on the New York City area, is venturing far afield, agreeing to buy Bresnan Communications, a cable company that operates in Colorado, Montana, Wyoming and Utah, for $1.365 billion. Rival bids had come from Time Warner Cable and Charter Communications. Providence Equity Partners acquired Bresnan in 2003 for $525 million. Cablevision is the nation's fifth-largest U.S. cable company; Bresnan, the 13th largest.