Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2019	Apr. 24, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	GRANITE CONSTRUCTION INC
Entity Central Index Key	0000861459
Trading Symbol	GVA
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		46,814,851