Consolidated Financial Statements Consolidated Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease in operating profit					$ (11,028)	$ 3,099
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	$ (600)	$ 600
Decrease in accounts receivable					(99,963)	(77,580)
Increase in operating expenses	(6,700)			$ (7,400)	$ (13,300)	(14,900)
Products customized to customer specifications that have no alternative use (percent)					90.00%
Net cash provided by operating activities					$ 55,169	57,921
Inventory, Net	(695,192)		$ (649,448)		(695,192)
Revenues	920,016			842,861	1,850,944	1,671,154
Gross Profit	398,717			372,984	804,525	736,066
Net income	99,149			109,795	228,564	$ 225,559
Decrease in receivables due to factoring	25,500			$ 4,700
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Revenues	1,900				2,500
Gross Profit	1,200				1,600
Net income	$ 900				$ 1,200
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