Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percent of employees covered by collective bargaining agreements	35.00%
Contributions	$ 132,996	$ 121,978	$ 134,197
Percentage of contribution by employer of each employee's contribution up to 3%	100.00%
Percentage of contribution by employer of each employee who contributes between 3% and 6%	50.00%
Contributions to Quanta 401(k) Plan	$ 50,700	45,900	41,400
Contributions to the deferred compensation plans	1,400	1,300	1,100
Discretionary contributions	0	0	0
Deferred compensation obligations included in other long-term liabilities	74,200	58,200
Investments in company-owned life insurance policies	73,800	56,500
Increase to fair market value of plan assets	8,600	6,900	7,900
Increase to fair market value of plan liabilities	$ 10,400	7,500	9,300
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of employee contribution, lower range	3.00%
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of employee contribution, lower range	6.00%
Multiemployer Defined Contribution and Other Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions	$ 213,400	$ 188,600	$ 201,300