Employee Benefit Plans - Summary of Weighted Average Assumptions used to Determine Benefit Information (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate	2.40%	3.29%	4.33%
Expected return on plan assets	3.70%	4.30%	4.30%
Interest crediting rates	0.71%	1.68%	3.01%
Pension Benefits \| Minimum
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase		0.50%	0.50%
Pension Benefits \| Maximum
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase		3.00%	3.00%
Other Post-retirement Benefits
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate	2.49%	3.38%	4.38%
Assumed health care cost trend rates [Abstract]
Initial health care cost trend rate	5.70%	6.00%	6.20%
Ultimate rate	4.50%	4.50%	4.50%
Other Post-retirement Benefits \| Minimum
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase	0.50%	0.50%	0.50%
Other Post-retirement Benefits \| Maximum
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase	3.00%	3.00%	3.00%
Other Post-retirement Benefits \| Non-qualified Plan Benefits
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate	1.07%	2.48%	3.78%
Interest crediting rates	0.71%	1.68%	3.01%

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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

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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

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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.

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- Definition

Weighted-average interest crediting rate used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate.

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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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- Definition

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

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