Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Basic, Two Class Method [Abstract]
Net income (loss) attributable to Granite, Earnings per share, Basic	$ (28,898)	$ 13,038	[1]	$ 1,419	[2]	$ (21,982)	$ 17,987	$ 37,121	$ 1,949	$ (11,773)	$ (36,423)	$ 45,283	$ 51,161
Less: net income allocated to participating securities											0	283	738
Net income (loss) allocated to common shareholders for basic calculation											(36,423)	45,000	50,423
Weighted average common stock outstanding, basic (in shares)											38,803	38,447	38,117
Net income (loss) per share, basic (in dollars per share)	$ (0.74)	$ 0.34	[1]	$ 0.04	[2]	$ (0.57)	$ 0.46	$ 0.96	$ 0.05	$ (0.31)	$ (0.94)	$ 1.17	$ 1.32
Earnings Per Share, Diluted, Two Class Method [Abstract]
Net income (loss) attributable to Grainte, Earnings per share, Diluted	(28,898)	13,038	[1]	1,419	[2]	(21,982)	17,987	37,121	1,949	(11,773)	(36,423)	45,283	51,161
Less: net income allocated to participating securities											0	279	732
Net income (loss) allocated to common shareholders for diluted calculation											$ (36,423)	$ 45,004	$ 50,429
Weighted average common shares outstanding, diluted (in shares)											38,803	39,076	38,473
Net income (loss) per share, diluted (in dollars per share)	$ (0.74)	$ 0.34	[1]	$ 0.04	[2]	$ (0.57)	$ 0.46	$ 0.94	$ 0.05	$ (0.31)	$ (0.94)	$ 1.15	$ 1.31

[1] Net income for the quarter ended September 30 is approximately $2.1 million ($3.0 million pre-tax) higher than the amount previously reported in our Quarterly Report Form 10-Q for the quarterly period ended September 30, 2013 of $4.5 million. The pre-tax adjustments were primarily related to (i) an over-accrual of pre-bid costs which affected selling, general and administrative expenses and accrued and other current liabilities in the amount of $1.4 million and (ii) a revision in equipment-related costs, which affected cost of revenue and property and equipment in the amount of $1.6 million.

[2] Net income for the quarter ended June 30 is approximately $1.4 million ($1.9 million pre-tax) lower than the amounts previously reported in our Form 10-Q for the quarter period ended June 30, 2013 of $3.2 million. The pre-tax adjustments were primarily related to equipment-related costs of $1.7 million.