Impact of Recently Issued Accounting Standards Impact of recently issued accounting standards table (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended							12 Months Ended
		Mar. 31, 2018		Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017		Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales		$ 6,875,613	[1]	$ 7,539,449	$ 6,856,108	$ 6,422,226	$ 5,736,780	[1]	$ 26,554,563
Cost of sales		6,006,669		6,610,269	6,013,541	5,598,202	4,975,583		23,197,595
Gross Profit		868,944					761,197
Selling, general, and administrative expenses		562,969					515,526
Depreciation and amortization		47,247					37,141
Restructuring, integration, and other charges		21,171					15,505
Costs and Expenses		632,949					568,172
Operating income		235,995		286,824	235,441	230,446	193,025		945,736
Equity in earnings (losses) of affiliated companies		(673)					925
Gain (loss) on investments, net		(2,452)					1,982
Post-retirement expense		1,231					1,800
Interest and other financing expense, net		45,179					38,249
Income before income taxes		186,460					155,883
Provision for income taxes		46,590					39,564
Consolidated net income		139,870					116,319
Noncontrolling interests		776					1,582
Net income attributable to shareholders		$ 139,094		53,653	134,064	99,722	$ 114,737		402,176
Diluted	[2]	$ 1.56					$ 1.27
Basic		$ 1.58					$ 1.29
Accounting standards update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax		$ 4,116
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales				7,633,870	6,953,740	6,465,346	$ 5,759,552		26,812,508
Cost of sales				6,703,742	6,110,382	5,641,380	4,999,665		23,455,169
Gross Profit							759,887
Selling, general, and administrative expenses							515,519
Depreciation and amortization							37,141
Restructuring, integration, and other charges							15,505
Costs and Expenses							568,165
Operating income				270,914	235,992	229,822	191,722		928,450
Equity in earnings (losses) of affiliated companies							925
Gain (loss) on investments, net							0
Post-retirement expense							0
Interest and other financing expense, net							38,073
Income before income taxes							154,574
Provision for income taxes							39,224
Consolidated net income							115,350
Noncontrolling interests							1,582
Net income attributable to shareholders				$ 53,885	$ 134,630	$ 99,679	$ 113,768		$ 401,962
Diluted	[2]						$ 1.26
Basic							$ 1.27
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales							$ (22,772)
Cost of sales							(24,082)
Gross Profit							1,310
Selling, general, and administrative expenses							7
Depreciation and amortization							0
Restructuring, integration, and other charges							0
Costs and Expenses							7
Operating income							1,303
Equity in earnings (losses) of affiliated companies							0
Gain (loss) on investments, net							1,982
Post-retirement expense							1,800
Interest and other financing expense, net							176
Income before income taxes							1,309
Provision for income taxes							340
Consolidated net income							969
Noncontrolling interests							0
Net income attributable to shareholders							$ 969
Diluted	[2]						$ 0.01
Basic							$ 0.01
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax		$ 18,238

[1] Includes sales related to the United States of $2,649,668 and $2,342,128 for the first quarter of 2018 and 2017, respectively.

[2] Stock-based compensation awards for the issuance of 415 and 244 for the first quarter of 2018 and 2017, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.