Benefit Plans Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ 70,490	$ 72,841
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	1,323	1,099
Noncurrent liabilities	58,944	61,748
Liabilities	60,267	62,847
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	94	86
Noncurrent liabilities	11,546	11,113
Liabilities	$ 11,640	$ 11,199

Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03(15))
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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