Segments (Schedule of net sales, adjusted EBITDA and certain other measures by reportable segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Net sales	$ 886,375	$ 797,547	$ 1,644,075	$ 1,524,965
Gross profit	211,687	191,655	389,884	358,272
Depreciation & amortization	17,558	17,139	34,371	33,821
Operating segments [Member] | Geographic divisions [Member]
Segment Reporting Information [Line Items]
Net sales	886,375	797,547	1,644,075	1,524,965
Gross profit	211,687	191,655	389,884	358,272
Depreciation & amortization	16,944	15,945	33,171	31,551
Adjusted EBITDA	71,321	67,717	118,724	120,696
Other reconciling items [Member] | Other reconciling items [Member]
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Gross profit	0	0	0	0
Depreciation & amortization	614	1,194	1,200	2,270
Adjusted EBITDA	$ (11,744)	$ (10,183)	$ (25,584)	$ (29,453)