Pension Plans, Retirement Benefits and Savings Plans (Details) - Assumptions - United States [Member]	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Pension Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, cash balance interest crediting rate (percent)	4.01%	4.01%
Assumptions used to determine benefit obligations, future compensation increase rate (percent)	4.00%	4.00%
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	6.75%	7.00%
Pension Plans [Member] \| Qualified Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	2.60%	3.28%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	3.50%	4.57%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	2.84%	4.02%
Pension Plans [Member] \| Nonqualified Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	2.44%	3.17%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	3.30%	4.40%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	2.73%	3.95%
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	2.27%	3.09%
Assumptions used to determine net periodic benefit cost, discount rate used to measure interest cost (percent)	2.67%	3.90%
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	4.00%	4.00%
Assumed health care cost trend rates, rate to which the cost trend rate is assumed to decline (ultimate trend rate) (percent)	4.50%	4.50%
Postretirement Benefit Plan Before Age 65 [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	6.75%	7.00%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2026	2026
Postretirement Benefit Plan Age 65 and Older [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	7.75%	8.25%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2027	2026

The interest rate used to adjust for the time value of money, used for service cost.

No definition available.

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- Definition

The interest rate used to adjust for the time value of money, used for interest cost.

+ 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

+ 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

+ 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

+ 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=118255775&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=118255775&loc=d3e2919-114920

+ 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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- Definition

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

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+ Details

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

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+ Details

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- Definition

Year ultimate health care cost trend rate is expected to be reached, in CCYY format.

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+ Details

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