Construction Joint Ventures - Schedule of Unconsolidated Construction Joint Ventures Assets and Liabilities (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Construction Joint Venture
Unconsolidated Construction Joint Venture Assets, Noncurrent Assets		$ 204,201	$ 219,825	$ 223,449
Equity in Construction Joint Ventures	[1]	262,421	231,887	226,385
Other Partners Interest in Partnerships [Member]
Construction Joint Venture
Unconsolidated Construction Joint Venture Assets		810,111	869,782	846,832
Unconsolidated Construction Joint Venture Liabilities	[2]	331,838	462,159	445,068
Reporting Entitys Interest in Joint Venture [Member]
Construction Joint Venture
Unconsolidated Construction Joint Venture Assets	[3],[4]	442,222	452,560	431,382
Unconsolidated Construction Joint Venture Liabilities		179,801	220,673	204,997
Cash and Cash Equivalents [Member]
Construction Joint Venture
Unconsolidated Construction Joint Venture Assets		242,028	289,940	333,751
Other Assets, Current and Longterm [Member]
Construction Joint Venture
Unconsolidated Construction Joint Venture Assets	[3]	806,104	812,577	721,014
Accounts Payable [Member]
Construction Joint Venture
Unconsolidated Construction Joint Venture Liabilities		$ 511,639	$ 682,832	$ 650,065

[1] Included in this balance and in accrued expenses and other current liabilities on the condensed consolidated balance sheets were amounts related to deficits in construction joint ventures that were $11.6 million, $15.9 million and $16.0 million as of September 30, 2018, December 31, 2017 and September 30, 2017, respectively

[2] Partners’ interest and adjustments includes amounts to reconcile total net assets as reported by our partners to Granite’s interest adjusted to reflect our accounting policies and estimates primarily related to contract forecast differences

[3] Included in this balance and in accrued expenses and other current liabilities on our condensed consolidated balance sheets were amounts related to performance guarantees that were $88.6 million as of both September 30, 2018 and December 31, 2017 and were $88.9 million as of September 30, 2017

[4] Included in this balance as of September 30, 2018, December 31, 2017 and September 30, 2017 was, $67.1 million, $74.3 million, and $77.6 million, respectively, related to Granite’s share of estimated cost recovery of customer affirmative claims. In addition, this balance included $12.5 million, $11.8 million and $11.1 million related to Granite’s share of estimated recovery of back charge claims as of September 30, 2018, December 31, 2017 and September 30, 2017, respectively