Employee and Retiree Benefit Plans - Plans' Benefit Obligations and Fair Value of Assets and Statement of Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in plan assets
Total beginning balance	$ 547,484	$ 487,094
Total ending balance		547,484	$ 487,094
Pension Benefits
Change in benefit obligation
Obligation at January 1	777,645	881,932
Service cost	7,964	8,994	8,279
Interest cost	27,835	26,168	27,047
Participant contributions	11	0
Actuarial loss (gain)	103,374	(57,378)
Medicare Part D subsidy	0	0
Exchange rate changes	7,687	(12,742)
Benefits paid	(41,247)	(41,132)
Prior Service Cost	0	737
Other	0	(28,934)
Obligation at December 31	883,269	777,645	881,932
Change in plan assets
Total beginning balance	487,094	563,825
Actual return on plan assets	70,893	(18,951)
Employer contributions	25,915	24,357
Participant contributions	11	0
Medicare Part D subsidy	0	0
Exchange rate changes	7,328	(12,071)
Benefits paid	(41,247)	(41,132)
Other	(2,510)	(28,934)
Total ending balance	547,484	487,094	563,825
Funded status and amounts recognized in the Consolidated Balance Sheets at December 31
Deferred charges and other assets	5,353	11,039
Other accrued liabilities	(8,810)	(9,175)
Deferred credits and other liabilities	(332,328)	(292,415)
Funded status and net plan liability recognized at December 31	(335,785)	(290,551)
Other Postretirement Benefits
Change in benefit obligation
Obligation at January 1	94,779	106,276
Service cost	1,559	1,965	1,601
Interest cost	3,864	3,427	3,444
Participant contributions	1,930	2,104
Actuarial loss (gain)	10,503	(13,778)
Medicare Part D subsidy	234	325
Exchange rate changes	30	(67)
Benefits paid	(4,498)	(5,473)
Prior Service Cost	0	0
Other	0	0
Obligation at December 31	108,401	94,779	106,276
Change in plan assets
Total beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	2,333	3,044
Participant contributions	1,930	2,104
Medicare Part D subsidy	234	325
Exchange rate changes	0	0
Benefits paid	(4,497)	(5,473)
Other	0	0
Total ending balance	0	0	$ 0
Funded status and amounts recognized in the Consolidated Balance Sheets at December 31
Deferred charges and other assets	0	0
Other accrued liabilities	(5,234)	(5,101)
Deferred credits and other liabilities	(103,167)	(89,678)
Funded status and net plan liability recognized at December 31	$ (108,401)	$ (94,779)