Equity (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				$ 870,121		$ 817,106
Purchase of common stock				(4,946)	[1]	(3,366)	[2]
Other transactions with shareholders	[3]			12,247		6,816
Transactions with noncontrolling interests, net				(1,827)		(1,808)
Net Income Attributable to Parent		$ 37,105	$ 30,759	40,047		31,812
Net income		38,087	32,180	46,034		33,109
Dividends on common stock				(15,439)		(15,352)
Stockholders' equity, ending balance		906,190	836,505	$ 906,190		$ 836,505
Shares Purchased for Tax Withholding for Share Based Compensation				111,000		103,000
Granite Construction [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				$ 839,237		$ 794,385
Purchase of common stock				(4,946)	[1]	(3,366)	[2]
Other transactions with shareholders	[3]			12,247		6,816
Transactions with noncontrolling interests, net				0		0
Net Income Attributable to Parent				40,047
Net income						31,812
Dividends on common stock				(15,439)		(15,352)
Stockholders' equity, ending balance		871,146	814,295	871,146		814,295
Noncontrolling Interest [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance				30,884		22,721
Purchase of common stock				0	[1]	0	[2]
Other transactions with shareholders	[3]			0		0
Transactions with noncontrolling interests, net				(1,827)		(1,808)
Net income				5,987		1,297
Dividends on common stock				0		0
Stockholders' equity, ending balance		$ 35,044	$ 22,210	$ 35,044		$ 22,210

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

[2] Represents 103,000 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.