The father of 10 "had quite a bit of material right in the house," said his wife, Sheila, with a laugh.
Those cartoons Mr. Decker crafted that did not appear in the New Yorker often found their way into such magazines as the Saturday Evening Post, Look, Colliers and Playboy.
And over the years, he also did illustrations for advertising campaigns. Among the best known was a 28-year Philadelphia Bulletin series, which ran until the 1960s, that centered on the slogan, "In Philadelphia, nearly everybody reads the Bulletin." A major feature of the campaign was "Mr. Nearly" - the only man around not reading the paper.
Also a watercolorist, Mr. Decker enjoyed painting during his hours at home, and his watercolor work earned recognition at exhibitions including shows at Rosemont College, the Philadelphia Country Club and the Wayne Art Center. The Philadelphia Sketch Club exhibited Mr. Decker's cartoons and drawings.
While cartooning for the New Yorker, which he did unitl 1970, Mr. Decker lived for many years in Connecticut, where he enjoyed sailing the waters of Long Island Sound with his wife and children.
He also had a keen interest in gardening and landscaping. Before living in Berwyn, he lived in Strafford.
Born and reared in Philadelphia, Mr. Decker had studied at Pennsylvania Museum School of Industrial Art, now the University of the Arts.
His parents, Christian F. and Lulu Mae Sigafoos Decker, were the founders of Decker's Stationery, formerly on Chestnut Street.
His first wife was Winifred Langston Decker, who died in 1949. A son, Philip, died in 1980.
Surviving are his wife of 38 years, Sheila Whelan Decker; sons, Nicholas, Gerart, Mark, Michael, Gregory, Thaddeus and Cameron; daughters, Irene Ross and Kimberly Alvord; 13 grandchildren, two great-grandchildren and a brother.
A Mass of Christian Burial will be said at 11 a.m. tomorrow at St. Isaac Jogues Church, Walker Road, Valley Forge. Interment is private.