Construction Contracts - Summary of Backlog (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue, Remaining Performance Obligation [Roll Forward]
Beginning backlog	$ 70,219	$ 193,742	$ 71,258	$ 242,622
New contracts/change orders	53,590	(12,461)	106,992	43,469
Work performed	(16,944)	(58,590)	(71,385)	(163,400)
Ending backlog	$ 106,865	$ 122,691	$ 106,865	$ 122,691
Minimum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected completion of contracts	12 months		12 months
Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected completion of contracts	18 months		18 months