UnitedHealth Group, which entered only a handful of health insurance exchanges in year one, is on track to participate in about about two dozen states in 2015, United executives said in an earnings call with investors. United expects to be profitable in the exchange market over the long term, but officials say it will fall short of its goal of 3 to 5 percent margins in that sector next year. In the Medicaid arena, United is on course to grow...