Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2016	Jul. 27, 2016
Entity Information [Line Items]
Entity Registrant Name	GRANITE CONSTRUCTION INC
Entity Central Index Key	0000861459
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		39,597,687