Presented in the table below are the components of net periodic benefit cost (credit): | | | | | | | | | | | | | | For the Three Months Ended March 31, | | | 2021 | | 2020 | | Components of net periodic pension benefit cost: | | | | | Service cost | $ | 9 | | | $ | 8 | | | Interest cost | 17 | | | 19 | | | Expected return on plan assets | (32) | | | (28) | | | Amortization of prior service credit | (1) | | | (1) | | | Amortization of actuarial loss | 7 | | | 8 | | | Net periodic pension benefit cost | $ | — | | | $ | 6 | | | | | | | Components of net periodic other postretirement benefit credit: | | | | | Service cost | $ | 1 | | | $ | 1 | | | Interest cost | 2 | | | 3 | | | Expected return on plan assets | (5) | | | (4) | | | Amortization of prior service credit | (8) | | | (8) | | | Amortization of actuarial loss | — | | | 1 | | | Net periodic other postretirement benefit credit | $ | (10) | | | $ | (7) | |
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