Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue
Total revenue	$ 3,562,459	$ 3,445,606	$ 3,287,031
Cost of revenue
Total cost of revenue	3,217,671	3,223,928	2,952,191
Gross profit	344,788	221,678	334,840
Selling, general and administrative expenses	353,320	307,981	272,776
Acquisition and integration expenses	53	15,299	61,520
Non-cash impairment charges (see Notes 10 and 12)	156,690	0	0
Gain on sales of property and equipment	(6,930)	(18,703)	(7,672)
Operating (loss) income	(158,345)	(82,899)	8,216
Other expense (income)
Interest income	(3,096)	(7,433)	(6,082)
Interest expense	24,200	18,374	14,571
Equity in income of affiliates, net	(8,783)	(11,454)	(6,935)
Other income, net	(4,203)	(5,308)	(1,666)
Total other expense (income)	8,118	(5,821)	(112)
(Loss) income before benefit from income taxes	(166,463)	(77,078)	8,328
Benefit from income taxes	(282)	(20,376)	(3,208)
Net (loss) income	(166,181)	(56,702)	11,536
Amount attributable to non-controlling interests	21,064	(3,489)	(10,954)
Net (loss) income attributable to Granite Construction Incorporated	$ (145,117)	$ (60,191)	$ 582
Net (loss) income per share attributable to common shareholders (See Note 18)
Basic (in dollars per share)	$ (3.18)	$ (1.29)	$ 0.01
Diluted (in dollars per share)	$ (3.18)	$ (1.29)	$ 0.01
Weighted average shares of common stock
Basic (in shares)	45,614	46,559	43,564
Diluted (in shares)	45,614	46,559	44,025
Transportation [Member]
Revenue
Total revenue	$ 2,017,989	$ 1,892,149	$ 1,946,750
Cost of revenue
Total cost of revenue	1,884,241	1,837,148	1,809,664
Water [Member]
Revenue
Total revenue	440,317	468,730	345,861
Cost of revenue
Total cost of revenue	386,076	438,964	286,727
Specialty [Member]
Revenue
Total revenue	723,391	727,537	625,666
Cost of revenue
Total cost of revenue	631,211	640,808	535,731
Materials [Member]
Revenue
Total revenue	380,762	357,190	368,754
Cost of revenue
Total cost of revenue	$ 316,143	$ 307,008	$ 320,069