Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2019	Jul. 30, 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	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		46,840,209
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	1-12911
Entity Tax Identification Number	770239383
Entity Address, Address Line One	585 W. Beach Street
Entity Address, City or Town	Watsonville
Entity Address, State or Province	California
Entity Address, Postal Zip Code	95076
City Area Code	831
Local Phone Number	724-1011