Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring gains									$ 2,411	$ 1,925	$ 6,003
Quarterly Financial Data [Abstract]
Revenue, Net	$ 801,274	$ 957,126	$ 762,913	$ 468,400	$ 666,681	$ 803,905	$ 604,579	$ 439,452	2,989,713	2,514,617	2,371,029
Gross profit	$ 100,707	$ 114,530	$ 74,570	$ 25,126	$ 81,250	$ 107,674	$ 73,201	$ 39,245	314,933	301,370	299,836
Gross profit as a percent of revenue	12.60%	12.00%	9.80%	5.40%	12.20%	13.40%	12.10%	8.90%
Net income (loss)	$ 35,325	$ 48,055	$ 16,272	$ (23,851)	$ 19,264	$ 38,172	$ 18,526	$ (9,762)	75,801	66,200	68,248
Net income (loss) as a percent of revenue	4.40%	5.00%	2.10%	(5.10%)	2.90%	4.70%	3.10%	(2.20%)
Net income (loss) attributable to Granite	$ 32,773	$ 45,982	$ 14,133	$ (23,790)	$ 16,173	$ 37,190	$ 14,199	$ (10,440)	$ 69,098	$ 57,122	$ 60,485
Net income (loss) attributable to Granite as a percent of revenue	4.10%	4.80%	1.90%	(5.10%)	2.40%	4.60%	2.30%	(2.40%)
Net (loss) income per share attributable to common shareholders:
Diluted (in dollars per share)	$ 0.81	$ 1.14	$ 0.35	$ (0.60)	$ 0.40	$ 0.92	$ 0.35	$ (0.27)	$ 1.71	$ 1.42	$ 1.52
Basic (in dollars per share)	$ 0.82	$ 1.15	$ 0.35	$ (0.60)	$ 0.41	$ 0.94	$ 0.36	$ (0.27)	$ 1.74	$ 1.44	$ 1.54
(Loss) income before (benefit from) provision for income taxes									$ (104,463)	$ (96,362)	$ (103,427)
Noncontrolling Interest [Member]
Quarterly Financial Data [Abstract]
Net income (loss)									$ 6,703	$ 9,078	7,763
Restructuring Type, Real Estate Asset Impairment [Member] | Enterprise Improvement Plan [Member] | Noncontrolling Interest [Member]
Net (loss) income per share attributable to common shareholders:
Restructuring and impairment (gains) charges, net											$ (3,300)