Disaggregation of Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 807,119	$ 762,913	$ 1,370,498	$ 1,231,313
Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	432,225	429,269	701,468	656,118
Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	273,946	254,463	522,360	461,496
Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	100,948	79,181	146,670	113,699
California [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	258,066	208,116	467,965	325,417
California [Member] | Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	187,901	147,605	351,997	230,369
California [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	14,971	12,048	27,786	22,169
California [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	55,194	48,463	88,182	72,879
Northwest [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	216,964	224,587	305,355	319,022
Northwest [Member] | Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	160,983	182,574	227,425	263,240
Northwest [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	12,360	11,295	21,575	14,962
Northwest [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	43,621	30,718	56,355	40,820
Heavy Civil [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	209,015	212,579	396,896	383,545
Heavy Civil [Member] | Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	7,055	24,098	12,255	33,318
Heavy Civil [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	201,960	188,481	384,641	350,227
Heavy Civil [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0	0	0	0
Kenny [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	101,593	117,631	178,801	203,329
Kenny [Member] | Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	56,938	74,992	90,443	129,191
Kenny [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	44,655	42,639	88,358	74,138
Kenny [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0	$ 0	0	$ 0
Water and Mineral Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	21,481		21,481
Water and Mineral Services [Member] | Construction Segment [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	19,348		19,348
Water and Mineral Services [Member] | Large Project Construction [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0		0
Water and Mineral Services [Member] | Construction Materials [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 2,133		$ 2,133