Pension and Other Postretirement Benefits (Details 8) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Securities, Global Entity [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 0
Equity Securities, Global Entity [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 462,507	396,222	$ 454,438
Pensions [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	88,634	73,668
Pensions [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	371,030	320,074
Pensions [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,843	2,480
Pensions [Member] | Cash and short-term investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,737	3,750
Pensions [Member] | Cash and short-term investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,737	3,750
Pensions [Member] | Cash and short-term investments [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Cash and short-term investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. large-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	40,538	36,821
Pensions [Member] | Equity Securities, U.S. large-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. large-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	40,538	36,821
Pensions [Member] | Equity Securities, U.S. large-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. mid-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	17,744	13,337
Pensions [Member] | Equity Securities, U.S. mid-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	17,744	13,337
Pensions [Member] | Equity Securities, U.S. mid-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. mid-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. small-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	16,116	13,244
Pensions [Member] | Equity Securities, U.S. small-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	16,116	13,244
Pensions [Member] | Equity Securities, U.S. small-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, U.S. small-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	146,013	123,084
Pensions [Member] | Equity Securities, International equities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, International equities [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	146,013	123,084
Pensions [Member] | Equity Securities, International equities [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Equity Securities, Global Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	51,037	43,337
Pensions [Member] | Equity Securities, Global Entity [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	51,037	43,337
Pensions [Member] | Equity Securities, Global Entity [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0
Pensions [Member] | Equity Securities, Global Entity [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0
Pensions [Member] | U.S. bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	124,429	117,249
Pensions [Member] | U.S. bond funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | U.S. bond funds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	124,429	117,249
Pensions [Member] | U.S. bond funds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | International bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	60,050	42,920
Pensions [Member] | International bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | International bonds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	60,050	42,920
Pensions [Member] | International bonds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,843	2,480
Pensions [Member] | Other [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Other [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pensions [Member] | Other [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 2,843	$ 2,480