Acquisitions (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
	Feb. 15, 2017	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Payment for Contingent Consideration Liability, Investing Activities					$ (4,250)
Sales		$ 263,759		$ 247,347	522,470	$ 468,372
Payments to Acquire Property, Plant, and Equipment					$ 14,528	$ 26,692
Effective Income Tax Rate Reconciliation, Percent					23.00%	9.90%
Futura Industries [Member]
Business Acquisition [Line Items]
Business Combination Contract Price	$ 92,000
Business Combination, Consideration Transferred	87,000
Business Combination, Contingent Consideration, Asset, Current					$ 5,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset				700		$ 700
Business Combinations Purchase Price Allocated Net of Contingent Consideration	$ 82,860
Payment for Contingent Consideration Liability, Investing Activities					4,300
Tax Recovery Life of Goodwill for Amortization	15 years
Percentage of outstanding equity interests acquired	100.00%
Goodwill, Purchase Accounting Adjustments			$ 100
Aluminum Extrusions
Business Acquisition [Line Items]
Income Loss From Ongoing Operations		$ 13,156		$ 11,772	$ 23,355	$ 21,601
Customer Relationships [Member] | Futura Industries [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	12 years
Trade Names [Member] | Futura Industries [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	13 years