CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue
Total revenue	$ 789,540	$ 807,119	$ 1,409,341	$ 1,370,498
Cost of revenue
Total cost of revenue	841,944	726,750	1,421,267	1,233,846
Gross (loss) profit	(52,404)	80,369	(11,926)	136,652
Selling, general and administrative expenses	69,998	61,316	151,153	122,568
Acquisition and integration expenses	9,177	26,287	12,500	34,696
Gain on sales of property and equipment	(4,935)	(1,505)	(6,835)	(2,048)
Operating loss	(126,644)	(5,729)	(168,744)	(18,564)
Other (income) expense
Interest income	(1,728)	(1,173)	(4,544)	(2,694)
Interest expense	4,158	3,203	8,172	5,638
Equity in income of affiliates	(2,594)	(3,534)	(3,884)	(3,758)
Other income, net	(759)	(940)	(2,521)	(672)
Total other income	(923)	(2,444)	(2,777)	(1,486)
Loss before (benefit from) provision for income taxes	(125,721)	(3,285)	(165,967)	(17,078)
(Benefit from) provision for income taxes	(31,760)	2,796	(40,925)	(1,335)
Net loss	(93,961)	(6,081)	(125,042)	(15,743)
Amount attributable to non-controlling interests	(3,875)	(2,304)	(7,368)	(4,065)
Net loss attributable to Granite Construction Incorporated	$ (97,836)	$ (8,385)	$ (132,410)	$ (19,808)
Net loss per share attributable to common shareholders (see Note 16)
Basic	$ (2.09)	$ (0.20)	$ (2.83)	$ (0.49)
Diluted	$ (2.09)	$ (0.20)	$ (2.83)	$ (0.49)
Weighted average shares of common stock
Basic	46,824	41,044	46,762	40,074
Diluted	46,824	41,044	46,762	40,074
Transportation [Member]
Revenue
Total revenue	$ 403,978	$ 502,711	$ 742,188	$ 861,856
Cost of revenue
Total cost of revenue	503,857	466,748	820,817	794,431
Water [Member]
Revenue
Total revenue	112,831	51,618	212,086	91,659
Cost of revenue
Total cost of revenue	101,568	46,168	192,704	74,645
Specialty [Member]
Revenue
Total revenue	175,084	151,842	315,777	270,313
Cost of revenue
Total cost of revenue	152,874	130,366	278,700	233,101
Materials [Member]
Revenue
Total revenue	97,647	100,948	139,290	146,670
Cost of revenue
Total cost of revenue	$ 83,645	$ 83,468	$ 129,046	$ 131,669