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Pension and Other Postretirement Benefits - Weighted Average assumptions used in calculating benefit obligations (Details) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Pension |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rate | 2.58% | 3.26%
Rate of compensation increase, group 1 | 3.00% | 3.00%
Rate of compensation increase, group 2 | 3.50% | 3.50%
Measurement date | Dec. 31, 2020 | Dec. 31, 2019
OPEB |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rate | 2.34% | 3.07%
Rate of compensation increase, group 1 | 3.00% | 3.00%
Rate of compensation increase, group 2 | 3.50% | 3.50%
Measurement date | Dec. 31, 2020 | Dec. 31, 2019

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- Definition The maximum expected rate of compensation increases (for pay-related plans). + References No definition available. + Details
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- Definition Measurement Date, Benefit Obligation + 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=118255775&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=118255775&loc=d3e1928-114920 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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