Benefit Plans Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ 108,044	$ 70,490
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	1,899	1,323
Noncurrent liabilities	92,820	58,944
Liabilities	94,719	60,267
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	96	94
Noncurrent liabilities	15,224	11,546
Liabilities	$ 15,320	$ 11,640