Summary of Significant Accounting Policies - Reclassification from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ (11,853)	$ 6,667	$ 4,256
Income tax expense (benefit)									(21,942)	65,609	(34,832)
Net income (loss) attributable to Tutor Perini Corporation	$ 35,495	$ 36,819	$ 18,709	$ 17,371	$ (86,117)	$ 19,313	$ (320,530)	$ (356)	108,394	(387,690)	83,436
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Pension Plan
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									2,407	1,933	2,052
Income tax expense (benefit)									(675)	(550)	(586)
Net income (loss) attributable to Tutor Perini Corporation									1,732	1,383	1,466
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gain (Loss) in Fair Value of Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									(315)	(76)	72
Income tax expense (benefit)									66	16	(15)
Net income (loss) attributable to Tutor Perini Corporation									$ (249)	$ (60)	$ 57