Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Information [Abstract]
Number of reportable segments			4
Segment Reporting Information [Line Items]
Net sales to external customers	$ 227,041	$ 214,624	$ 747,554	$ 692,569
Intersegment sales	16,189	23,819	54,590	54,562
Gross profit	49,443	46,400	166,320	163,074
Gross profit (in hundredths)	21.80%	21.60%	22.20%	23.50%
Segment profit (loss)	7,549	9,689	30,596	35,062
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	7,549	9,689	30,596	35,062
Net income attributable to non-controlling interest in subsidiary	(48)	(41)	(124)	(74)
Elimination of intersegment profit	(649)	(1,925)	(1,009)	(3,035)
Net income attributable to controlling interest	6,852	7,723	29,463	31,953
Asphalt Group [Member]
Segment Reporting Information [Line Items]
Number of business units			3
Net sales to external customers	46,797	50,458	174,898	192,396
Intersegment sales	5,860	10,032	19,910	20,387
Gross profit	9,563	8,508	37,735	44,486
Gross profit (in hundredths)	20.40%	16.90%	21.60%	23.10%
Segment profit (loss)	2,248	500	13,541	20,421
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	2,248	500	13,541	20,421
Aggregate and Mining Group [Member]
Segment Reporting Information [Line Items]
Number of business units			7
Net sales to external customers	91,860	83,232	278,024	248,647
Intersegment sales	5,939	6,309	19,256	18,453
Gross profit	22,957	20,682	72,512	61,838
Gross profit (in hundredths)	25.00%	24.80%	26.10%	24.90%
Segment profit (loss)	8,697	7,764	29,836	23,114
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	8,697	7,764	29,836	23,114
Mobile Asphalt Paving Group [Member]
Segment Reporting Information [Line Items]
Number of business units			3
Net sales to external customers	36,618	39,143	123,770	142,565
Intersegment sales	4,276	6,504	13,759	13,069
Gross profit	7,575	10,091	28,331	39,158
Gross profit (in hundredths)	20.70%	25.80%	22.90%	27.50%
Segment profit (loss)	1,631	4,976	9,634	20,819
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	1,631	4,976	9,634	20,819
Underground Group [Member]
Segment Reporting Information [Line Items]
Number of business units			3
Net sales to external customers	29,179	23,769	100,738	58,524
Intersegment sales	57	974	1,497	2,653
Gross profit	4,929	4,080	15,285	8,137
Gross profit (in hundredths)	16.90%	17.20%	15.20%	13.90%
Segment profit (loss)	518	511	1,001	(3,166)
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	518	511	1,001	(3,166)
All Others [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	22,587	18,022	70,124	50,437
Intersegment sales	57	0	168	0
Gross profit	4,419	3,039	12,457	9,455
Gross profit (in hundredths)	19.60%	16.90%	17.80%	18.70%
Segment profit (loss)	(5,545)	(4,062)	(23,416)	(26,126)
Reconciliation of total segment profits to the Company's consolidated totals [Abstract]
Total segment profits	$ (5,545)	$ (4,062)	$ (23,416)	$ (26,126)