Illinois is taking a novel approach to getting its residents to save for retirement. Starting in 2017, most state residents who don’t already have a retirement plan at work will be automatically enrolled in individual retirement accounts, funded through a 3 percent deduction from their paychecks. The program will be created under a law signed by Gov. Pat Quinn on Sunday. Participation will be voluntary, but workers who don’t want to save will need to opt out manually. (They will also be allowed to save more than 3 percent if they wish.) An estimate produced by the plan’s backers found...