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Pension And Other Retirement Benefits - Summary of Pension Plan Assets by Category Based on Hierarchy of Fair Value Measurements (Detail) - Pension Plans - U.S. Plans - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 460 | $ 449 | $ 420
Percent of total assets | 100.00% | 100.00% |
Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 26 | $ 25 |
Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | 365 | 356 |
Measured using NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | 69 | 68 |
Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 2 | $ 5 |
Percent of total assets | 0.00% | 1.00% |
Cash and cash equivalents | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 2 | $ 5 |
Total equity investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 139 | $ 147 |
Percent of total assets | 30.00% | 33.00% |
Total equity investments | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 139 | $ 147 |
U.S. large-cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 114 | $ 106 |
Percent of total assets | 25.00% | 24.00% |
U.S. large-cap | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 114 | $ 106 |
U.S. small and mid-cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 25 | $ 21 |
Percent of total assets | 5.00% | 5.00% |
U.S. small and mid-cap | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 25 | $ 21 |
Emerging markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets |  | $ 20 |
Percent of total assets |  | 4.00% |
Emerging markets | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets |  | $ 20 |
Total fixed-income investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 295 | $ 272 |
Percent of total assets | 65.00% | 60.00% |
Total fixed-income investments | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 26 | $ 25 |
Total fixed-income investments | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | 224 | 204 |
Total fixed-income investments | Measured using NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | 45 | 43 |
Emerging markets bond fund |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 30 | $ 29 |
Percent of total assets | 7.00% | 6.00% |
Emerging markets bond fund | Measured using NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 30 | $ 29 |
Intermediate-term investment grade U.S. government/ corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 57 | $ 60 |
Percent of total assets | 12.00% | 13.00% |
Intermediate-term investment grade U.S. government/ corporate bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 57 | $ 60 |
Long duration corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 146 | $ 144 |
Percent of total assets | 32.00% | 32.00% |
Long duration corporate bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 146 | $ 144 |
U.S. Treasury Inflation-Protected Securities (TIPs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 26 | $ 25 |
Percent of total assets | 6.00% | 6.00% |
U.S. Treasury Inflation-Protected Securities (TIPs) | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 26 | $ 25 |
Emerging markets equity mutual fund |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 21 |  |
Percent of total assets | 5.00% |  |
Emerging markets equity mutual fund | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 21 |  |
Private investment fund—high yield securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 15 | $ 14 |
Percent of total assets | 3.00% | 3.00% |
Private investment fund—high yield securities | Measured using NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 15 | $ 14 |
Other investment—private real estate fund |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 24 | $ 25 |
Percent of total assets | 5.00% | 6.00% |
Other investment—private real estate fund | Measured using NAV practical expedient |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total assets | $ 24 | $ 25 |

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