Goodwill and Other Intangibles (Changes in the Net Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Balance at beginning of period	$ 121,829	$ 68,253
Adjustments	(185)	(28)
Additions	84,795	53,604
Impairments	(24,254)	0
Balance at end of period	182,185	121,829
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	24,254	0
Joining materials
Goodwill [Roll Forward]
Balance at beginning of period	16,210	16,238
Adjustments	(11)	(28)
Additions	0	0
Impairments	0	0
Balance at end of period	16,199	16,210
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	0	0
Tubing
Goodwill [Roll Forward]
Balance at beginning of period	1,895	1,895
Adjustments	0	0
Additions	0	0
Impairments	0	0
Balance at end of period	1,895	1,895
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	0	0
Building materials
Goodwill [Roll Forward]
Balance at beginning of period	71,388	50,120
Adjustments	0	0
Additions	0	21,268
Impairments	0	0
Balance at end of period	71,388	71,388
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	0	0
Performance materials
Goodwill [Roll Forward]
Balance at beginning of period	32,336	0
Adjustments	(174)	0
Additions	0	32,336
Balance at end of period	7,908	32,336
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	24,254	0
Electrical products
Goodwill [Roll Forward]
Balance at beginning of period	0
Adjustments	0
Additions	84,795
Impairments	0
Balance at end of period	84,795	$ 0
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated impairment losses	$ 0