CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue
Total revenue	$ 1,055,591	$ 957,126	$ 2,426,089	$ 2,188,439
Cost of revenue
Total cost of revenue	911,100	842,596	2,144,946	1,974,213
Gross profit	144,491	114,530	281,143	214,226
Selling, general and administrative expenses	70,769	49,501	193,337	162,726
Acquisition and integration expenses	9,334	0	44,030	0
Gain on sales of property and equipment	(3,018)	(1,753)	(5,066)	(2,830)
Operating income	67,406	66,782	48,842	54,330
Other (income) expense
Interest income	(1,533)	(1,141)	(4,227)	(3,356)
Interest expense	4,452	2,660	10,090	8,097
Equity in income of affiliates	(1,769)	(2,732)	(5,527)	(4,907)
Other income, net	(1,533)	(1,309)	(2,205)	(2,821)
Total other income	(383)	(2,522)	(1,869)	(2,987)
Income before provision for income taxes	67,789	69,304	50,711	57,317
Provision for income taxes	8,692	21,249	7,357	16,841
Net income	59,097	48,055	43,354	40,476
Amount attributable to non-controlling interests	(3,425)	(2,073)	(7,490)	(4,151)
Net income attributable to Granite Construction Incorporated	$ 55,672	$ 45,982	$ 35,864	$ 36,325
Net income per share attributable to common shareholders (see Note 15)
Basic	$ 1.20	$ 1.15	$ 0.84	$ 0.91
Diluted	$ 1.17	$ 1.14	$ 0.84	$ 0.90
Weighted average shares of common stock
Basic	46,308	39,844	42,443	39,774
Diluted	47,810	40,387	42,910	40,367
Dividends per common share	$ 0.13	$ 0.13	$ 0.39	$ 0.39
Transportation [Member]
Revenue
Total revenue	$ 610,847	$ 624,727	$ 1,472,703	$ 1,423,396
Cost of revenue
Total cost of revenue	539,871	559,187	1,334,302	1,303,489
Water [Member]
Revenue
Total revenue	124,292	36,378	215,951	100,944
Cost of revenue
Total cost of revenue	100,189	34,573	174,834	91,172
Specialty [Member]
Revenue
Total revenue	190,836	197,886	461,149	452,265
Cost of revenue
Total cost of revenue	162,737	170,089	395,838	395,529
Materials [Member]
Revenue
Total revenue	129,616	98,135	276,286	211,834
Cost of revenue
Total cost of revenue	$ 108,303	$ 78,747	$ 239,972	$ 184,023