Benefit Plans - Estimated Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Benefits
Benefit payments expected to be paid over the next ten years
2018	$ 16,926
2019	16,630
2020	16,359
2021	16,014
2022	15,539
2023 to 2027	72,013
Other Benefits
Benefit payments expected to be paid over the next ten years
2018	1,292
2019	1,355
2020	1,434
2021	1,458
2022	1,525
2023 to 2027	$ 8,546

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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