Disaggregation of Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 563,379	$ 468,400
Construction Segment
Disaggregation Of Revenue [Line Items]
Total revenue	269,243	226,849
Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	248,414	207,033
Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	45,722	34,518
California [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	209,899	117,301
California [Member] | Construction Segment
Disaggregation Of Revenue [Line Items]
Total revenue	164,096	82,764
California [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	12,815	10,121
California [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	32,988	24,416
Northwest [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	88,391	94,435
Northwest [Member] | Construction Segment
Disaggregation Of Revenue [Line Items]
Total revenue	66,442	80,666
Northwest [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	9,215	3,667
Northwest [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	12,734	10,102
Heavy Civil [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	187,881	170,966
Heavy Civil [Member] | Construction Segment
Disaggregation Of Revenue [Line Items]
Total revenue	5,200	9,220
Heavy Civil [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	182,681	161,746
Kenny [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	77,208	85,698
Kenny [Member] | Construction Segment
Disaggregation Of Revenue [Line Items]
Total revenue	33,505	54,199
Kenny [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 43,703	$ 31,499