Employee and Retiree Benefit Plans (Fair Value Measurements of Retirement Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 563,825	$ 519,357
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	97,758	92,478
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	428,117	392,765
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	37,950	34,114
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	351,292	321,782
United States [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	97,758	92,478
United States [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	215,584	195,190
United States [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	37,950	34,114
United States [Member] | Defined Benefit Plan, Equity Securities, US Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	67,343	61,554
United States [Member] | Defined Benefit Plan, Equity Securities, US Core [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	67,343	61,554
United States [Member] | Defined Benefit Plan, Equity Securities, US Small/Midcap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	24,544	23,103
United States [Member] | Defined Benefit Plan, Equity Securities, US Small/Midcap [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	24,544	23,103
United States [Member] | Defined Benefit Plan, Equity Securities, Hedged Funds And Other Alternative Strategies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	50,522	48,113
United States [Member] | Defined Benefit Plan, Equity Securities, Hedged Funds And Other Alternative Strategies [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	12,572	13,999
United States [Member] | Defined Benefit Plan, Equity Securities, Hedged Funds And Other Alternative Strategies [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	37,950	34,114
United States [Member] | Defined Benefit Plan, Equity Securities, International Commingled Trust Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	83,960	67,451
United States [Member] | Defined Benefit Plan, Equity Securities, International Commingled Trust Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	83,960	67,451
United States [Member] | Defined Benefit Plan, Equity Securities, Emerging Market Commingled Equity Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	20,774	16,006
United States [Member] | Defined Benefit Plan, Equity Securities, Emerging Market Commingled Equity Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	20,774	16,006
United States [Member] | Defined Benefit Plan, Fixed Income Securities, US Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	79,890	78,473
United States [Member] | Defined Benefit Plan, Fixed Income Securities, US Fixed Income [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	79,890	78,473
United States [Member] | Defined Benefit Plan, Fixed Income Securities, International Commingled Trust Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	13,122	13,486
United States [Member] | Defined Benefit Plan, Fixed Income Securities, International Commingled Trust Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	13,122	13,486
United States [Member] | Defined Benefit Plan, Fixed Income Securities, Emerging Market Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,266	5,775
United States [Member] | Defined Benefit Plan, Fixed Income Securities, Emerging Market Mutual Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,266	5,775
United States [Member] | Defined Benefit Plan, Cash And Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,871	7,821
United States [Member] | Defined Benefit Plan, Cash And Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,871	7,821
Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	212,533	197,575
Foreign Plans [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	212,533	197,575
Foreign Plans [Member] | Defined Benefit Plan, Cash And Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	6,888	4,929
Foreign Plans [Member] | Defined Benefit Plan, Cash And Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	6,888	4,929
Foreign Plans [Member] | Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	78,666	74,108
Foreign Plans [Member] | Defined Benefit Plan, Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	78,666	74,108
Foreign Plans [Member] | Defined Benefit Plan, Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	103,314	97,075
Foreign Plans [Member] | Defined Benefit Plan, Fixed Income Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	103,314	97,075
Foreign Plans [Member] | Defined Benefit Plan, Diversified Pooled Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	23,665	21,463
Foreign Plans [Member] | Defined Benefit Plan, Diversified Pooled Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 23,665	$ 21,463