Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2014 USD ($) segment $ / shares	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2014 USD ($) $ / shares
Change in Accounting Estimate [Line Items]
Number of Civil segment projects | segment		2
Income from construction operations	$ 30,881	$ 65,443	$ 50,965	$ 106,940
Net income	$ 11,777	$ 28,545	$ 16,903	$ 44,484
Diluted earnings per common share (in dollars per share) | $ / shares	$ 0.24	$ 0.58	$ 0.34	$ 0.91
Civil Segment Project One [Member]
Change in Accounting Estimate [Line Items]
Impact on results of operations		$ 24,200
Civil Segment Project Two [Member]
Change in Accounting Estimate [Line Items]
Impact on results of operations		(9,400)
Changes In Estimates [Member]
Change in Accounting Estimate [Line Items]
Income from construction operations	$ 14,700	14,800		$ 14,800
Net income	$ (8,700)	$ 8,800		$ 8,800
Diluted earnings per common share (in dollars per share) | $ / shares	$ (0.17)	$ 0.18		$ 0.18
Tutor Perini Corporation [Member]
Change in Accounting Estimate [Line Items]
Income from construction operations	$ 18,799	$ 11,082	$ 20,223	$ 26,320
Net income	$ 11,777	$ 28,545	$ 16,903	$ 44,484