General - Effect of the Adoption of ASU 2014-09 and 2017-07 (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on net sales	$ 1,951,230	$ 1,926,722	$ 3,931,737	$ 3,922,408
Effect on cost of sales	1,518,446	1,459,242	3,050,450	2,992,709
Effect on gross profit	432,784	467,480	881,287	929,699
Effect on selling and distribution	336,721	338,010	682,717	683,073
Effect on general and administrative	65,972	72,281	141,494	170,945
Effect on total operating costs and expenses	473,676	421,263	906,834	879,431
Effect on operating income	(40,892)	46,217	(25,547)	50,268
Effect on other (income) expense, net	$ 782	248	$ 1,252	391
Accounting Standards Update 2017-07
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on cost of sales		(100)		(194)
Effect on gross profit		100		194
Effect on selling and distribution		(134)		(267)
Effect on general and administrative		(819)		(1,691)
Effect on total operating costs and expenses		(953)		(1,958)
Effect on operating income		1,053		2,152
Effect on other (income) expense, net		1,053		2,152
Pro Forma Results Assuming Retrospective Adoption of ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on net sales		2,063,926		4,230,615
Effect on cost of sales		1,596,546		3,301,110
Effect on gross profit		467,380		929,505
Increase (Decrease) to Previously Reported Amounts | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on net sales		137,204		308,207
Effect on cost of sales		137,204		308,207
Effect on gross profit		0		0
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on net sales		1,926,722		3,922,408
Effect on cost of sales		1,459,342		2,992,903
Effect on gross profit		467,380		929,505
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect on cost of sales		1,459,342		2,992,903
Effect on gross profit		467,380		929,505
Effect on selling and distribution		338,144		683,340
Effect on general and administrative		73,100		172,636
Effect on total operating costs and expenses		422,216		881,389
Effect on operating income		45,164		48,116
Effect on other (income) expense, net		$ (805)		$ (1,761)