Business, Basis of Presentation and Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Number of reportable segments | segment	5
Cash	$ 40,326	$ 38,767	$ 4,984	$ 24,059
Book overdrafts	30,000	39,900
Inventory obsolescence reserves	7,700	3,500
Financing costs incurred	6,300		2,400
Deferred financing costs, net of accumulated amortization	13,000	9,800
Self-Insurance [Member] | Workers' Compensation Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	1,500
Self-Insurance [Member] | General Liability Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	3,000
Self-Insurance [Member] | Property Insurance Policy [Member] | Automobiles [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	3,000
Self-Insurance [Member] | Umbrella Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Maximum annual coverage limit, per claim	100,000
Maximum annual coverage limit, in aggregate	100,000
Self-Insurance [Member] | Employee Group Medical Claims Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Loss contingency, maximum loss per employee	500
Interest Expense [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Amortization of deferred financing costs	3,300	3,200	$ 2,900
2017 Acquisitions [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Goodwill, measurement period adjustments	2,700
Proportionately Consolidated Joint Ventures [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Cash	$ 17,300	$ 7,700