Employee Benefit Plans - Weighted-average Assumptions Used to Determine Benefit Obligations (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Discount rate used to determine pension expense :
Discount rate	3.22%	3.64%	4.18%
Discount rate used to determine value of obligations
Discount rate	4.23%	4.23%	3.64%
Long term rate of return	7.00%	7.00%	7.00%
Retirement Plan
Discount rate used to determine pension expense :
Discount rate	2.85%	3.40%	3.75%
Discount rate used to determine value of obligations
Discount rate	4.00%	4.00%	3.40%

Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long Term Return on Assets

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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 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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