Construction Joint Ventures (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Construction Joint Venture
Contracts Revenue	$ 579,146	$ 464,624	$ 1,235,264	$ 1,005,457
Net cash provided by operating activities			64,614	(19,398)
Unconsolidated Construction Joint Venture
Construction Joint Venture
Performance Guarantees	88,900	83,100	88,900	83,100	$ 83,100
Granite Construction [Member] | Unconsolidated Construction Joint Venture
Construction Joint Venture
Unconsolidated Construction Joint Venture Net (Loss) Income	(7,100)	10,300	(15,300)	15,900
Partnership Interest [Member] | Unconsolidated Construction Joint Venture
Construction Joint Venture
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures	$ 5,100,000		$ 5,100,000
Joint Venture Consolidated | Consolidated Construction Joint Venture
Construction Joint Venture
Number of Active Joint Venture Projects	6		6
Contracts Revenue	$ 44,500	24,800	$ 129,500	79,900
Net cash provided by operating activities			26,400	7,800
Joint Venture Consolidated | Minimum | Consolidated Construction Joint Venture
Construction Joint Venture
Construction Contract Value	49,200		49,200
Revenue Remaining to be Recognized on Consolidated Construction Joint Ventures	$ 8,100		$ 8,100
Proportionate Share of the Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly	50.00%		50.00%
Joint Venture Consolidated | Maximum | Consolidated Construction Joint Venture
Construction Joint Venture
Construction Contract Value	$ 409,600		$ 409,600
Revenue Remaining to be Recognized on Consolidated Construction Joint Ventures	$ 204,800		$ 204,800
Proportionate Share of the Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly	65.00%		65.00%
Joint Venture Unconsolidated | Unconsolidated Construction Joint Venture
Construction Joint Venture
Unconsolidated Construction Joint Venture Net (Loss) Income	$ 31,000	38,700	$ 57,200	68,000
Number of Active Joint Venture Projects	11		11
Number of Active Joint Venture Projects Greater than $1Billion	3		3
Joint Venture Unconsolidated | Line Item Joint Venture
Construction Joint Venture
Number of Active Joint Venture Projects	1		1
Contracts Revenue	$ 5,400	$ 9,500	$ 20,100	$ 23,500
Joint Venture Unconsolidated | Minimum | Unconsolidated Construction Joint Venture
Construction Joint Venture
Construction Contract Value	$ 77,300		$ 77,300
Proportionate Share of the Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly	20.00%		20.00%
Joint Venture Unconsolidated | Minimum | Line Item Joint Venture
Construction Joint Venture
Construction Contract Value	$ 66,200		$ 66,200
Revenue Per Project Remaining to be Recognized on Line Item Construction Joint Ventures	3,800		3,800
Joint Venture Unconsolidated | Maximum | Unconsolidated Construction Joint Venture
Construction Joint Venture
Construction Contract Value	$ 3,700,000		$ 3,700,000
Proportionate Share of the Joint Ventures Equity Owned by or Beneficial Interest in the Reporting Entity Directly or Indirectly	50.00%		50.00%
Reporting Entitys Interest in Joint Venture [Member] | Unconsolidated Construction Joint Venture
Construction Joint Venture
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures	$ 1,700,000		$ 1,700,000
Reporting Entitys Interest in Joint Venture [Member] | Minimum | Unconsolidated Construction Joint Venture
Construction Joint Venture
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures	500		500
Reporting Entitys Interest in Joint Venture [Member] | Minimum | Line Item Joint Venture
Construction Joint Venture
Construction Contract Value	48,700		48,700
Reporting Entitys Interest in Joint Venture [Member] | Maximum | Unconsolidated Construction Joint Venture
Construction Joint Venture
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures	408,100		408,100
Other Partners Interest in Partnerships [Member] | Unconsolidated Construction Joint Venture
Construction Joint Venture
Revenue Remaining to be Recognized on Unconsolidated Construction Joint Ventures	$ 3,400,000		$ 3,400,000