Summary of Significant Accounting Policies (Tax Effects of Componenets of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Defined benefit pension plan adjustments, Before-Tax Amount		$ 1,180	$ 1,079	$ 2,416
Defined benefit pension plan adjustments, Tax (Expense) Benefit		(336)	(308)	(992)
Defined benefit pension plan adjustments, Net-of-Tax Amount		844	771	1,424
Foreign currency translation adjustment, Before-Tax Amount		1,867	(4,067)	2,159
Foreign currency translation adjustment, Tax (Expense) Benefit		(530)	1,122	(886)
Foreign currency translation adjustment, Net-of-Tax Amount		1,337	(2,945)	1,273
Unrealized gain (loss) in fair value of investments, Before-Tax Amount		1,982	(1,005)	(4)
Unrealized gain (loss) in fair value of investments, Tax (Expense) Benefit		(421)	227	2
Unrealized gain (loss) in fair value of investments, Net-of-Tax Amount		1,561	(778)	(2)
Total other comprehensive income (loss), Before-Tax Amount		5,029	(3,993)	4,571
Total other comprehensive income (loss), Tax Benefit		(1,287)	1,041	(1,876)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX		3,742	(2,952)	2,695
Less: Other comprehensive income (loss) attributable to noncontrolling interests, Before-Tax Amount	[1]	393	(221)
Less: Other comprehensive income (loss) attributable to noncontrolling interests, Net-of-Tax Amount	[1]	393	(221)
Total other comprehensive income (loss) attributable to Tutor Perini Corporation, Before-Tax Amount		4,636	(3,772)	4,571
Total other comprehensive income (loss) attributable to Tutor Perini Corporation, Tax (Expense) Benefit		(1,287)	1,041	(1,876)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAX		$ 3,349	$ (2,731)	$ 2,695

[1] The only component of other comprehensive income (loss) attributable to noncontrolling interests is foreign currency translation.