A thermoplastic composition comprises A) 25 to 95 parts by weight of a first polycarbonate consisting essentially of i) 25 to 100 mole percent of a first carbonate unit comprising an alkyl-substituted bisphenol carbonate unit, ii) 0 to 75 mole percent of a second carbonate unit where the first and second carbonate units are not identical, and the sum of the mole percentages of the first and second carbonate units in the first polycarbonate is 100 mole percent; B) 5 to 75 parts by weight of a polyester-polycarbonate where the molar ratio of carbonate unit to arylate ester unit is 95:5 to 10:90; and C) 0 to 65 parts by weight of a second polycarbonate, where the first polycarbonate and second polycarbonate are not identical, and the sum of the parts by weight of the first polycarbonate, the polyester-polycarbonate, and the second polycarbonate is 100 parts by weight.