CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 53,741	$ 75,801	$ 66,200
Other comprehensive (loss) income, net of tax:
Net unrealized (loss) gain on derivatives	(451)	191	184
Less: reclassification for net (gains) losses included in interest expense	(214)	159	319
Net change	(665)	350	503
Foreign currency translation adjustments, net	(718)	655	626
Other comprehensive (loss) income	(1,383)	1,005	1,129
Comprehensive income	52,358	76,806	67,329
Non-controlling interests in comprehensive income	(11,331)	(6,703)	(9,078)
Comprehensive income attributable to Granite Construction Incorporated	$ 41,027	$ 70,103	$ 58,251