Summary of Significant Accounting Policies (Tax Effects of Componenets of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Defined benefit pension plan adjustments, Before-Tax Amount	$ 2,416	$ (4,452)	$ 31
Defined benefit pension plan adjustments, Tax (Expense) Benefit	(992)	1,829	1,995
Defined benefit pension plan adjustments, Net-of-Tax Amount	1,424	(2,623)	2,026
Foreign currency translation adjustment, Before-Tax Amount	2,159	(439)	(5,897)
Foreign currency translation adjustment, Tax (Expense) Benefit	(886)	178	2,683
Foreign currency translation adjustment, Net-of-Tax Amount	1,273	(261)	(3,214)
Unrealized (loss) gain in fair value of investments, Before-Tax Amount	(4)	(576)	1,123
Unrealized (loss) gain in fair value of investments, Tax (Expense) Benefit	2	236	(357)
Unrealized (loss) gain in fair value of investments, Net-of-Tax Amount	(2)	(340)	766
Unrealized loss in fair value of interest rate swap, Before-Tax Amount		(45)	(37)
Unrealized loss in fair value of interest rate swap, Tax (Expense) Benefit		21	(88)
Unrealized loss in fair value of interest rate swap, Net-of-Tax Amount		(24)	(125)
Total other comprehensive income (loss), Before-Tax Amount	4,571	(5,512)	(4,780)
Total other comprehensive income (loss), Tax Benefit	(1,876)	2,264	4,233
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	2,695	(3,248)	(547)
Total other comprehensive income (loss) attributable to Tutor Perini Corporation, Before-Tax Amount	4,571	(5,512)	(4,780)
Total other comprehensive income (loss) attributable to Tutor Perini Corporation, Tax (Expense) Benefit	(1,876)	2,264	4,233
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAX	$ 2,695	$ (3,248)	$ (547)