Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance			$ 827,663		$ 795,635
Purchase of common stock			(4,521)	[1]	(3,840)	[2]
Other transactions with shareholders			7,690	[3]	7,589	[3]
Transactions with noncontrolling interests, net			(8,022)	[4]	(17,489)	[4]
Comprehensive income (loss):
Net income	45,746	42,376	41,546		41,293
Dividends on common stock			(15,082)		(15,078)
Stockholders' equity, ending balance	849,274	808,110	849,274		808,110
Shares Purchased for Tax Withholding for Share Based Compensation			154,000		138,000
Granite Construction [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance			799,197		761,031
Purchase of common stock			(4,521)	[1]	(3,840)	[2]
Other transactions with shareholders			7,690	[3]	7,589	[3]
Transactions with noncontrolling interests, net			0	[4]	0	[4]
Comprehensive income (loss):
Net income					32,407
Dividends on common stock			(15,082)		(15,078)
Stockholders' equity, ending balance	814,581	782,109	814,581		782,109
Noncontrolling Interest [Member]
Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance			28,466		34,604
Purchase of common stock			0	[1]	0	[2]
Other transactions with shareholders			0	[3]	0	[3]
Transactions with noncontrolling interests, net			(8,022)	[4]	(17,489)	[4]
Comprehensive income (loss):
Net income			14,249		8,886
Dividends on common stock			0		0
Stockholders' equity, ending balance	$ 34,693	$ 26,001	$ 34,693		$ 26,001

[1] Represents 154,000 shares purchased in connection with employee tax withholding for shares/units granted under our Amended and Restated 1999 Equity Incentive Plan.

[2] Represents 138,000 shares purchased in connection with employee tax withholding for shares/units granted under our Amended and Restated 1999 Equity Incentive Plan.

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

[4] Amounts are comprised primarily of distributions to noncontrolling partners.