Retirement Plans, Amounts Recognized in Accumulated Other Comprehensive Income Table (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ (249)	$ (303)
Net actuarial loss	37,075	50,238
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive (income) loss	36,827	49,935
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	(533)	(588)
Net actuarial loss	126	(17)
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive (income) loss	$ (406)	$ (605)

Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (i-k)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580

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Balance Type:	debit
Period Type:	instant