Acquisitions (Narrative) (Details) - USD ($) $ in Thousands				3 Months Ended								12 Months Ended
	Dec. 01, 2015	Sep. 01, 2015	May 01, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Inventory step-up charges												$ 2,884	$ 10,285	$ 0
Net sales				$ 747,574	$ 821,204	$ 797,547	$ 727,418	$ 510,162	$ 416,471	$ 357,287	$ 292,826	3,093,743	1,576,746	1,311,498
Income from continuing operations before income taxes												45,146	(14,520)	$ 28,455	$ 27,900
SBS [Member]
Business Acquisition [Line Items]
Date of acquisition	Dec. 01, 2015
Gross contractual value of accounts receivable	$ 129,200
Fair value of accounts receivable	124,526
Inventory step-up charges	13,200											$ 2,900	10,300
Net sales													103,600
Income from continuing operations before income taxes													18,600
Acquired cash	$ 6,342
VNS [Member]
Business Acquisition [Line Items]
Date of acquisition			May 01, 2015
Net sales													103,100
Income from continuing operations before income taxes													4,700
Purchase price			$ 47,100
Acquired cash			$ 2,344
RBI [Member]
Business Acquisition [Line Items]
Date of acquisition		Sep. 01, 2015
Net sales													27,000
Income from continuing operations before income taxes													$ 1,200
Purchase price		$ 102,400
Customer relationships [Member] | SBS [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	16 years 6 months
Customer relationships [Member] | VNS [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years
Customer relationships [Member] | RBI [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Trademarks [Member] | SBS [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 9 months 18 days
Trademarks [Member] | VNS [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			2 years
Non-compete Agreements [Member] | SBS [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year
Non-compete Agreements [Member] | RBI [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		3 years