It is not exactly an idiom, Ramesh; it is a fixed expression or saying, and it is used as an interjection or comment clause, grammatically independent of the rest of the utterance. The CEO of BP apologized for his company's oil spill in the Gulf of Mexico, and then he went off to attend a sailing regatta in England! Well, actions speak louder than words: he obviously is not very troubled about the oil spill.
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