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Retirement Plans and Other Postretirement Benefits - Weighted-Average Assumptions for Pensions and Other Benefits (Details) | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Weighted-average assumptions used to determine benefit obligations |  |  |
Rate of compensation increase (as a percent) | 4.00% | 4.00% |
Initial pre-65 healthcare cost trend rate (as a percent) | 6.00% | 6.50% |
Initial pre-65 ultimate health care cost trend rate (as a percent) | 4.75% | 4.75% | 4.75%
Number of years to ultimate trend rate (pre-65 participants) | 4 years | 5 years |
Initial post-65 healthcare cost trend rate (as a percent) | 2.00% | 2.00% |
Interest crediting rate – cash balance pension plans | 4.50% | 4.50% |
Weighted-average assumptions used to determine net periodic benefit costs |  |  |
Initial pre-65 health care cost trend rate (as a percent) | 6.50% | 7.00% | 7.00%
Initial pre-65 ultimate healthcare cost trend rate (as a percent) | 4.75% | 4.75% | 4.75%
Number of years to ultimate trend rate (pre-65 participants) | 4 years | 5 years | 7 years
Initial post-65 health care cost trend rate (as a percent) | 2.00% | 4.75% | 4.75%
Interest crediting rate – cash balance pension plans | 4.50% | 4.50% | 4.50%
Pension Benefits |  |  |
Weighted-average assumptions used to determine benefit obligations |  |  |
Discount rate (as a percent) | 2.92% | 2.53% |
Weighted-average assumptions used to determine net periodic benefit costs |  |  |
Discount rate (as a percent) | 2.53% | 3.30% | 4.34%
Rate of compensation increase (as a percent) | 4.00% | 4.00% | 4.00%
Expected long-term return on plan assets (as a percent) | 5.30% | 5.75% | 6.25%
Other Benefits |  |  |
Weighted-average assumptions used to determine benefit obligations |  |  |
Discount rate (as a percent) | 2.98% | 2.63% |
Weighted-average assumptions used to determine net periodic benefit costs |  |  |
Discount rate (as a percent) | 2.63% | 3.42% | 4.39%
Expected long-term return on plan assets (as a percent) | 4.90% | 4.85% | 5.40%

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- Definition Defined Benefit Plan, Post-65 Health Care Cost Trend Rate Assumed for Next Fiscal Year, Used in Calculating Benefit Obligation + References No definition available. + Details
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- Definition Defined Benefit Plan, Pre-65 Health Care Cost Trend Rate Assumed for Next Fiscal Year + References No definition available. + Details
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- Definition Defined Benefit Plan, Pre-65 Health Care Cost Trend Rate Assumed for Next Fiscal Year, Used in Calculating Benefit Obligation + References No definition available. + Details
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- Definition Defined Benefit Plan, Pre-65 Participant, Period after which Rate Reaches Ultimate Trend Rate, used in Calculating Benefit Costs + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(4) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2919-114920 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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