Equity (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				$ 922,591		$ 870,121
Purchase of common stock				(6,713)	[1]	(4,946)	[2]
Other transactions with shareholders	[3]			14,488		11,345
Transactions with noncontrolling interests, net				(3,502)		(1,827)
Net income		$ 45,982	$ 37,191	36,325		40,949
Net Income Attributable to Noncontrolling Interest		2,073	982	4,151		5,987
Net income		48,055	38,173	40,476		46,936
Dividends on common stock				(15,532)		(15,439)
Stockholders' equity, ending balance		951,808	906,190	$ 951,808		$ 906,190
Shares Purchased for Tax Withholding for Share Based Compensation				136,000		111,000
Granite Construction [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				$ 885,988		$ 839,237
Purchase of common stock				(6,713)	[1]	(4,946)	[2]
Other transactions with shareholders	[3]			14,488		11,345
Transactions with noncontrolling interests, net				0		0
Net income				36,325		40,949
Dividends on common stock				(15,532)		(15,439)
Stockholders' equity, ending balance		914,556	871,146	914,556		871,146
Noncontrolling Interest [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				36,603		30,884
Purchase of common stock				0	[1]	0	[2]
Other transactions with shareholders	[3]			0		0
Transactions with noncontrolling interests, net				3,502		1,827
Net Income Attributable to Noncontrolling Interest		4,151	5,987
Dividends on common stock				0		0
Stockholders' equity, ending balance		$ 37,252	$ 35,044	$ 37,252		$ 35,044

[1] Represents 136,000 shares purchased in connection with employee tax withholding for restricted stock units vested under our 2012 Equity Incentive Plan.

[2] Represents 111,000 shares purchased in connection with employee tax withholding for restricted stock units vested under our 2012 Equity Incentive Plan.

[3] Amounts are comprised primarily of amortized restricted stock units.