AMR Corporation (parent company of American Airlines) reported the following (in millions). Compute AMR Corporation's pension expense. (Enter answer in millions.) Pension expense millions At December 31, 2017, Sheffield Corporation had a projected benefit obligation of $606, 100, plan assets of $337, 100, and prior service cost of $129, 800 in accumulated other comprehensive income. Determine the pension asset/liability at December 31, 2017. (Enter liability using either a negative sign preceding the number e.g. -45 or parenthesis e.g. (45).) Pension asset/liability at December 31, 2017 $