Reportable Segments (Capital Expenditures, Depreciation and Total Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Capital Expenditures	$ 25,622	$ 15,225	$ 12,658
Depreciation and Amortization	40,097	18,380	13,137
Assets	836,520	624,673
Inactive properties
Segment Reporting Information [Line Items]
Assets	6,300	7,300
Operating segments
Segment Reporting Information [Line Items]
Assets	836,520	624,673
Operating segments | Joining materials
Segment Reporting Information [Line Items]
Capital Expenditures	3,667	4,064	5,128
Depreciation and Amortization	4,030	3,026	3,204
Assets	100,028	98,441
Operating segments | Tubing
Segment Reporting Information [Line Items]
Capital Expenditures	4,325	3,997	2,835
Depreciation and Amortization	2,786	2,571	2,401
Assets	36,573	35,544
Operating segments | Building materials
Segment Reporting Information [Line Items]
Capital Expenditures	11,399	4,570	2,661
Depreciation and Amortization	5,802	5,598	5,217
Assets	177,393	166,923
Operating segments | Performance materials
Segment Reporting Information [Line Items]
Capital Expenditures	1,991	576	0
Depreciation and Amortization	9,089	4,885	0
Assets	93,413	126,985
Operating segments | Electrical products
Segment Reporting Information [Line Items]
Capital Expenditures	2,327	0	0
Depreciation and Amortization	16,242	0	0
Assets	294,901	0
Operating segments | Kasco
Segment Reporting Information [Line Items]
Capital Expenditures	1,913	1,969	1,989
Depreciation and Amortization	1,991	2,147	2,162
Assets	22,293	22,878
Corporate and reconciling items
Segment Reporting Information [Line Items]
Capital Expenditures	0	49	45
Depreciation and Amortization	157	153	$ 153
Assets	$ 111,919	$ 173,902