Exploring Mark Rothko's paintings on paper
His abstract expressionist canvases are among the most recognizable of all 20th century artists' works. But Mark Rothko (1903-1970) also produced nearly 3,000 pieces on paper – smaller in scale but just as innovative. CBS News chief election & campaign correspondent Robert Costa visits an exhibition at the National Gallery of Art in Washington, D.C., that explores the trail of paper works the artist left behind, and talks with curator Adam Greenhalgh, and with the artist's children, Kate Rothko Prizel and Christopher Rothko, about Rothko's remarkable vision.