Table:
|  |  |  | As of and for the Years Ended December 31, |  |  |
| --- | --- | --- | --- | --- | --- |
|  | 2017 | Recognition of Net Periodic Benefits Expense | Deferrals | Net Change in AOCL | 2018 |
|  |  |  | (Dollars in millions) |  |  |
| Accumulated other comprehensive loss: |  |  |  |  |  |
| Pension plans: |  |  |  |  |  |
| Net actuarial (loss) gain | $(2,892) | 179 | (260) | (81) | (2,973) |
| Prior service benefit (cost) | 54 | (8) | — | (8) | 46 |
| Deferred income tax benefit (expense)(1) | 1,107 | (418) | 65 | (353) | 754 |
| Total pension plans | (1,731) | (247) | (195) | (442) | (2,173) |
| Post-retirement benefit plans: |  |  |  |  |  |
| Net actuarial (loss) gain | (250) | — | 257 | 257 | 7 |
| Prior service (cost) benefit | (107) | 20 | — | 20 | (87) |
| Deferred income tax benefit (expense)(2) | 122 | (37) | (63) | (100) | 22 |
| Total post-retirement benefit plans | (235) | (17) | 194 | 177 | (58) |
| Total accumulated other comprehensive loss | $(1,966) | (264) | (1) | (265) | (2,231) |
Paragraphs:
The following table presents cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2017, items recognized as a component of net periodic benefits expense in 2018, additional items deferred during 2018 and cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2017. The items not recognized as a component of net periodic benefits expense have been recorded on our consolidated balance sheets in accumulated other comprehensive loss:
(1) Amounts currently recognized in net periodic benefits expense include $375 million of benefit arising from the adoption of ASU 2018-02. See Note 1— Background and Summary of Significant Accounting Policies for further detail.
(2) Amounts currently recognized in net periodic benefits expense include $32 million arising from the adoption of ASU 2018-02. See Note 1— Background and Summary of Significant Accounting Policies for further detail.
Question:
What is the sum of the prior service benefit (cost) for pension plans in 2017 and 2018?
Answer: 54+46 = 100