Retirement Plans and Postretirement Medical Benefits (Other Changes in Plan Assets and Benefit Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Document Fiscal Year Focus	2019
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	$ 6,931	$ (11,837)
Amortization of net actuarial loss	(2,026)	(3,048)
Amortization of prior service credit (cost)	(321)	(304)
Settlements and curtailments	0	(246)
Total recognized in other comprehensive income	4,584	(15,435)
United States
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	(8,459)	50,534
Plan amendment	0	0
Amortization of net actuarial loss	(26,146)	(31,298)
Amortization of prior service credit (cost)	60	60
Net transition asset	0	0
Settlements and curtailments	(2,381)	(44,665)
Total recognized in other comprehensive income	(36,926)	(25,369)
Foreign
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	3,643	3,824
Plan amendment	0	9,009
Amortization of net actuarial loss	(6,337)	(7,264)
Amortization of prior service credit (cost)	(243)	71
Net transition asset	6	7
Settlements and curtailments	(397)	13
Total recognized in other comprehensive income	$ (3,328)	$ 5,660