Earnings Per Share Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 4,455	$ 45,746	$ (12,205)	$ 41,546
Earnings Per Share, Basic, Two Class Method [Abstract]
Net income (loss) attributable to Granite, Earnings per share, Basic	10,997	37,121	(8,267)	27,297
Participating Securities, Distributed and Undistributed Earnings	0	181	0	184
Net Income (Loss) Available to Common Stockholders, Basic	10,997	36,940	(8,267)	27,113
Weighted average shares of common stock - Basic	38,876	38,518	38,773	38,418
Earnings (Loss) Per Share, Basic	$ 0.28	$ 0.96	$ (0.21)	$ 0.71
Earnings Per Share, Diluted, Two Class Method [Abstract]
Net income (loss) attributable to Granite, Earnings per share, Diluted	10,997	37,121	(8,267)	27,297
Undistributed Earnings Allocated to Participating Securities	0	178	0	181
Net Income (Loss) Available to Common Stockholders, Diluted	$ 10,997	$ 36,943	$ (8,267)	$ 27,116
Weighted average shares of common stock - Diluted	39,759	39,141	38,773	39,013
Earnings (Loss) Per Share, Diluted	$ 0.28	$ 0.94	$ (0.21)	$ 0.70