Construction and Line Item Joint Ventures - Schedule of Unconsolidated Construction Joint Ventures Assets and Liabilities (Details) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Construction Joint Venture [Line Items]
Deficit in unconsolidatedconstruction joint venture		$ 13,100		$ 13,100
Equity in Construction Joint Ventures Current Assets Excluding Deficit in Equity	[1]	206,572	$ 181,259	206,572	$ 181,259	$ 184,575
Granite Construction [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Revenue		11,100	1,800	29,700	28,100
Partnership Interest [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures		$ 5,600,000		$ 5,600,000
Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Number of Active Joint Venture Projects		3		3
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		$ 530,215	313,945	$ 1,439,766	1,055,276
Unconsolidated Construction Joint Venture Cost of Revenue		424,492	338,848	1,270,793	982,014
Unconsolidated Construction Joint Venture Revenue		$ 19,500	25,200	$ 86,900	75,200
Joint Venture Unconsolidated [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Number of Active Joint Venture Projects		5		5
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		403,648	293,467	403,648	293,467	291,254
Unconsolidated Construction Joint Venture Liabilities		197,076	112,208	197,076	112,208	106,679
Unconsolidated Construction Joint Venture Revenue		147,750	100,877	421,201	313,825
Unconsolidated Construction Joint Venture Cost of Revenue		136,708	99,187	391,140	285,381
Unconsolidated Construction Joint Venture Gross Profit Loss		11,042	1,690	30,061	28,444
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		3,900,000		3,900,000
Unconsolidated Construction Joint Venture Assets		875,629	530,585	875,629	530,585	546,907
Unconsolidated Construction Joint Venture Liabilities		441,627	269,264	441,627	269,264	251,412
Unconsolidated Construction Joint Venture Revenue		382,465	213,068	1,018,565	741,451
Unconsolidated Construction Joint Venture Cost of Revenue		287,784	239,661	879,653	696,633
Minimum [Member] | Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 600		$ 600
Proportionate Share of the Consolidated Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly		50.00%		50.00%
Minimum [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 73,600		$ 73,600
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		$ 42,400		$ 42,400
Revenue Per Project Remaining to be Recognized on Line Item Construction Joint Ventures		1,300		1,300
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		3,200		3,200
Minimum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		28,500		28,500
Maximum [Member] | Joint Venture Consolidated [Member] | Consolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		$ 293,800		$ 293,800
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		$ 3,400,000		$ 3,400,000
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		$ 87,100		$ 87,100
Revenue Per Project Remaining to be Recognized on Line Item Construction Joint Ventures		39,800		39,800
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		632,200		632,200
Maximum [Member] | Reporting Entitys Interest in Joint Venture [Member] | Line Item Joint Venture [Member]
Construction Joint Venture [Line Items]
Construction Contract Value		64,600		64,600
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]	460,668	286,040	460,668	286,040	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		818,609	538,012	818,609	538,012	573,898
Accounts Payable [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Liabilities		228,695	141,630	228,695	141,630	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]	321,103	178,781	321,103	178,781	156,604
Accrued Liabilities [Member] | Joint Venture Unconsolidated [Member] | Unconsolidated Construction Joint Venture [Member]
Construction Joint Venture [Line Items]
Unconsolidated Construction Joint Venture Liabilities		$ 88,905	$ 61,061	$ 88,905	$ 61,061	$ 55,289

[1] As of September 30, 2015, this balance included $13.1 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.