Employee Benefits Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension expense from continuing operations
Pension lump sum settlement expense	$ 0	$ 0	$ 97,231
Amortization of:
Postretirement benefit income	61,215	41,704	138,656
Company-administered plans:
Pension expense from continuing operations
Service cost	12,977	13,820	13,023
Interest cost	94,476	88,013	100,909
Expected return on plan assets	(90,588)	(98,892)	(115,410)
Pension lump sum settlement expense	0	0	97,231
Amortization of:
Net actuarial gain	31,777	30,741	23,573
Prior service loss (credit)	2,976	(306)	(1,788)
Postretirement benefit income	51,618	33,376	117,538
Company-administered plans: | U.S.
Amortization of:
Postretirement benefit income	53,319	34,986	118,797
Company-administered plans: | Foreign
Amortization of:
Postretirement benefit income	(1,701)	(1,610)	(1,259)
Union-administered plans
Amortization of:
Postretirement benefit income	$ 9,597	$ 8,328	$ 21,118