Segment Information, Segment Information (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020 USD ($) segment	Mar. 31, 2020 segment	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) business	Jun. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	2	3
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	$ 265,299		$ 304,802	$ 554,147	$ 630,582
Gross profit	59,615		83,317	133,636	160,167
Net income	9,305		23,361	$ 29,788	37,579
Infrastructure Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Number of business units | business				13
Net sales	181,851		197,965	$ 384,469	417,214
Materials Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Number of business units | business				10
Net sales	83,448		106,837	$ 169,678	213,368
Corporate
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	0		0	0	0
Gross profit	$ 111		$ 81	$ 204	$ 76
Gross profit percent	0.00%		0.00%	0.00%	0.00%
Net income	$ (13,605)		$ (12,563)	$ (16,528)	$ (25,471)
Operating Segments
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	265,299		304,802	554,147	630,582
Gross profit	$ 59,615		$ 83,317	$ 133,636	$ 160,167
Gross profit percent	22.50%		27.30%	24.10%	25.40%
Net income	$ 9,079		$ 22,852	$ 29,411	$ 36,691
Operating Segments | Infrastructure Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	181,851		197,965	384,469	417,214
Gross profit	$ 38,290		$ 57,743	$ 91,213	$ 109,053
Gross profit percent	21.10%		29.20%	23.70%	26.10%
Net income	$ 14,215		$ 26,926	$ 31,435	$ 44,996
Operating Segments | Materials Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	83,448		106,837	169,678	213,368
Gross profit	$ 21,214		$ 25,493	$ 42,219	$ 51,038
Gross profit percent	25.40%		23.90%	24.90%	23.90%
Net income	$ 8,469		$ 8,489	$ 14,504	$ 17,166
Intersegment Eliminations
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	19,162		12,726	33,377	26,575
Net income	226		509	377	888
Intersegment Eliminations | Infrastructure Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	12,340		6,944	18,281	16,036
Intersegment Eliminations | Materials Solutions
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	6,822		5,782	15,096	10,539
Intersegment Eliminations | Corporate
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Net sales	$ 0		$ 0	$ 0	$ 0