Employee Benefit Plans - Assumptions Used to Determine Benefit Obligations and Pension Plan Investment Strategy (Details)	Dec. 31, 2019	Dec. 31, 2018
Pension Plan
Weighted average assumptions used to determine the year-end benefit obligations
Discount rate (as a percent)	3.30%	4.30%
Pension Plan \| Domestic equity securities
Normal target allocation
Normal target allocation (as a percent)	55.00%
Pension Plan \| International equity securities
Normal target allocation
Normal target allocation (as a percent)	10.00%
Pension Plan \| Bonds
Normal target allocation
Normal target allocation (as a percent)	35.00%
Supplemental Employee Retirement Plan (SERP)
Weighted average assumptions used to determine the year-end benefit obligations
Discount rate (as a percent)	5.02%	5.03%
Rate of compensation increase (as a percent)	5.00%	5.00%

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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://fasb.org/us-gaap/role/ref/legacyRef
-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

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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://fasb.org/us-gaap/role/ref/legacyRef
-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

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- References

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