Schedule of Unconsolidated Construction Joint Ventures Assets and Liabilities (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Construction Joint Venture [Line Items]
Equity in Construction Joint Ventures Current Assets Excluding Deficit in Equity	[1]	$ 208,248	$ 185,859	$ 208,248	$ 185,859	$ 184,575
Granite Construction [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Revenue		7,300	23,200	18,600	25,700
Partnership Interest [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		$ 5,700,000		$ 5,700,000
Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Number of Active Joint Venture Projects		2		2
Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Number of Active Joint Venture Projects		11		11
Unconsolidated Construction Joint Venture Revenue		$ 466,144	392,165	$ 909,551	741,331
Unconsolidated Construction Joint Venture Cost of Revenue		436,230	345,704	846,301	643,166
Unconsolidated Construction Joint Venture Revenue		$ 34,000	49,400	$ 67,400	100,400
Joint Venture Unconsolidated [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Number of Active Joint Venture Projects		4		4
Reporting Entitys Interest in Joint Venture [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		$ 1,700,000		$ 1,700,000
Unconsolidated Construction Joint Venture Assets		380,968	291,360	380,968	291,360	291,254
Unconsolidated Construction Joint Venture Liabilities		172,720	105,501	172,720	105,501	106,679
Unconsolidated Construction Joint Venture Revenue		138,164	123,639	273,451	212,948
Unconsolidated Construction Joint Venture Cost of Revenue		130,408	99,639	254,432	186,194
Unconsolidated Construction Joint Venture Gross Profit Loss		7,756	24,000	19,019	26,754
Other Partners Interest in Partnerships [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		4,000,000		4,000,000
Unconsolidated Construction Joint Venture Assets		771,875	572,753	771,875	572,753	546,907
Unconsolidated Construction Joint Venture Liabilities		385,506	254,865	385,506	254,865	251,412
Unconsolidated Construction Joint Venture Revenue		327,980	268,526	636,100	528,383
Unconsolidated Construction Joint Venture Cost of Revenue		305,822	246,065	591,869	456,972
Minimum [Member] | Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 32,700		$ 32,700
Proportionate Share of the Consolidated Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly		55.00%		55.00%
Minimum [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 73,000		$ 73,000
Proportionate Share of the Consolidated Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly		20.00%		20.00%
Minimum [Member] | Joint Venture Unconsolidated [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 43,400		$ 43,400
Revenue Per Project Remaining to be Recognized on Line Item Construction Joint Ventures		2,000		2,000
Minimum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		4,600		4,600
Minimum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		29,500		29,500
Maximum [Member] | Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 284,700		$ 284,700
Proportionate Share of the Consolidated Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly		65.00%		65.00%
Maximum [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 3,100,000		$ 3,100,000
Proportionate Share of the Consolidated Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly		50.00%		50.00%
Maximum [Member] | Joint Venture Unconsolidated [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 87,000		$ 87,000
Revenue Per Project Remaining to be Recognized on Line Item Construction Joint Ventures		19,400		19,400
Maximum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		649,500		649,500
Maximum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		64,500		64,500
Cash and Cash Equivalents [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Assets	[2]	336,581	226,217	336,581	226,217	264,263
Other Assets, Current and Longterm [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Assets		816,262	637,896	816,262	637,896	573,898
Accounts Payable [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Liabilities		216,663	133,914	216,663	133,914	146,198
Billings in Excess of Costs and Estimated Earnings [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Liabilities	[2]	276,982	162,951	276,982	162,951	156,604
Accrued Liabilities [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Liabilities		$ 64,581	$ 63,501	$ 64,581	$ 63,501	$ 55,289

[1] As of June 30, 2015, this balance included $0.8 million of deficit in construction joint ventures that is included in accrued expenses and other current liabilities on the condensed consolidated balance sheet.

[2] The volume and stage of completion of contracts from our unconsolidated construction joint ventures may cause fluctuations in cash and cash equivalents as well as billings in excess of costs and estimated earnings and costs in excess of billings and estimated earnings between periods. The decision to distribute joint venture cash and cash equivalents and assets must generally be made jointly by all of the partners and, accordingly, these cash and cash equivalents and assets generally are not available for the working capital needs of Granite until distributed.