Construction Contracts - Summary of Backlog (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue, Remaining Performance Obligation [Roll Forward]
Beginning backlog	$ 38,838	$ 235,642	$ 71,258	$ 242,622
New contracts/change orders	50,278	15,490	53,402	55,930
Work performed	(18,897)	(57,390)	(54,441)	(104,810)
Ending backlog	$ 70,219	$ 193,742	$ 70,219	$ 193,742
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