Consolidated Financial Statements Consolidated Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease in operating profit					$ (386)	$ (9,423)
Tax Cuts and jobs act, income tax expense (benefit)			$ 139,200
Tax Cuts and jobs act, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense	$ (8,000)	$ 600
Decrease in accounts receivable					(93,198)	(94,945)
Increase in operating expenses	(6,700)			$ (8,700)	$ (20,000)	23,600
Products customized to customer specifications that have no alternative use (percent)					90.00%
Net cash provided by operating activities					$ 201,958	199,489
Inventory, Net	(719,508)		$ (649,448)		(719,508)
Revenues	907,548			872,940	2,758,492	2,544,094
Gross Profit	400,666			380,398	1,205,192	1,116,464
Net income	95,716			110,261	324,281	$ 335,820
Decrease in receivables due to factoring	11,400			$ 12,100
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Revenues	800				3,300
Gross Profit	600				2,200
Net income	$ 500				$ 1,600
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Prepaid Expense and Other Assets							$ 4,400
Inventory, Net							1,700
Taxes Payable							600
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect							$ 2,100