A bit for drilling a wellbore includes: a shank having a coupling formed at an upper end thereof; a body removably attached to a lower end of the shank and having a blade receptacle formed therethrough; a blade fixed to the body; a plurality of superhard cutters mounted along a leading edge of the fixed blade; a blade disposed in the blade receptacle and longitudinally movable relative to the body between an extended position and a retracted position; a plurality of superhard cutters mounted along a leading edge of the movable blade; and a spring disposed between the shank and the movable blade and biasing the movable blade toward the extended position.