Basis of Presentation - Summary of Impact of Adoption of Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Assets
Receivables, net	$ 492,718	$ 484,245	$ 492,718	$ 484,245		$ 479,791
Contract assets	265,190	0	265,190	0	$ 160,890	0
Costs and estimated earnings in excess of billings	0	99,883	0	99,883		103,965
Other current assets	49,100	43,597	49,100	43,597		36,513
Deferred income taxes, net	25,135	0	25,135	0		0
Liabilities and equity
Contract liabilities	91,864	0	91,864	0	$ 83,674	0
Billings in excess of costs and estimated earnings	0	114,180	0	114,180		135,146
Accrued expenses and other current liabilities	293,959	231,048	293,959	231,048		236,407
Deferred income taxes, net	5,759		5,759
Retained earnings	737,417	715,451	737,417	715,451		$ 783,699
Revenue
Revenue	807,119	762,913	1,370,498	1,231,313
Cost of revenue
Cost of revenue	726,750	688,343	1,233,846	1,131,617
Gross profit	80,369	74,570	136,652	99,696
Operating (loss) income	(5,729)	23,989	(18,564)	(12,452)
Provision for (benefit from) income taxes	2,796	8,088	(1,335)	(4,408)
Net (loss) income	(6,081)	16,272	(15,743)	(7,579)
Net (loss) income attributable to Granite Construction Incorporated	(8,385)	14,133	(19,808)	(9,657)
Construction Segment [Member]
Revenue
Revenue	432,225	429,269	701,468	656,118
Cost of revenue
Cost of revenue	370,674	368,369	601,521	567,889
Large Project Construction [Member]
Revenue
Revenue	273,946	254,463	522,360	461,496
Cost of revenue
Cost of revenue	272,608	$ 253,974	500,656	$ 458,452
Accounting Standards Update 2014-09 [Member] | Balances Without Adoption of Topic 606 [Member]
Assets
Receivables, net	615,782		615,782
Contract assets	0		0
Costs and estimated earnings in excess of billings	175,265		175,265
Other current assets	49,813		49,813
Deferred income taxes, net	19,863		19,863
Liabilities and equity
Contract liabilities	0		0
Billings in excess of costs and estimated earnings	119,335		119,335
Accrued expenses and other current liabilities	282,222		282,222
Deferred income taxes, net	5,759		5,759
Retained earnings	750,263		750,263
Cost of revenue
Gross profit	80,093		133,584
Operating (loss) income	(6,005)		(21,632)
Provision for (benefit from) income taxes	2,746		(2,048)
Net (loss) income	(6,307)		(18,098)
Net (loss) income attributable to Granite Construction Incorporated	(8,611)		(22,163)
Accounting Standards Update 2014-09 [Member] | Balances Without Adoption of Topic 606 [Member] | Construction Segment [Member]
Revenue
Revenue	433,509		702,989
Cost of revenue
Cost of revenue	370,674		601,521
Accounting Standards Update 2014-09 [Member] | Balances Without Adoption of Topic 606 [Member] | Large Project Construction [Member]
Revenue
Revenue	274,228		520,849
Cost of revenue
Cost of revenue	274,450		503,734
Accounting Standards Update 2014-09 [Member] | Effect of Change Higher/(Lower) [Member]
Assets
Receivables, net	(123,064)		(123,064)
Contract assets	265,190		265,190
Costs and estimated earnings in excess of billings	(175,265)		(175,265)
Other current assets	(713)		(713)
Deferred income taxes, net	5,272		5,272
Liabilities and equity
Contract liabilities	91,864		91,864
Billings in excess of costs and estimated earnings	(119,335)		(119,335)
Accrued expenses and other current liabilities	11,737		11,737
Deferred income taxes, net	0		0
Retained earnings	(12,846)		(12,846)
Cost of revenue
Gross profit	276		3,068
Operating (loss) income	276		3,068
Provision for (benefit from) income taxes	50		713
Net (loss) income	226		2,355
Net (loss) income attributable to Granite Construction Incorporated	226		2,355
Accounting Standards Update 2014-09 [Member] | Effect of Change Higher/(Lower) [Member] | Construction Segment [Member]
Revenue
Revenue	(1,284)		(1,521)
Cost of revenue
Cost of revenue	0		0
Accounting Standards Update 2014-09 [Member] | Effect of Change Higher/(Lower) [Member] | Large Project Construction [Member]
Revenue
Revenue	(282)		1,511
Cost of revenue
Cost of revenue	$ (1,842)		$ (3,078)