Acquisitions - Summary of Changes in Preliminary Calculations of the Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		3 Months Ended
	May 04, 2022	Mar. 31, 2023	Sep. 30, 2022	Dec. 31, 2022
Purchase Price Allocation:
Goodwill		$ 53,082		$ 53,210
McMahon Associates, Inc. (“McMahon”)
Business Acquisition [Line Items]
Total Purchase Price	$ 18,200	18,189
Purchase Price Allocation:
Accounts Receivable, net		8,456
Contract assets		1,017
Prepaid and other current assets		291
Property and equipment, net		949
Intangible assets		3,392
Other assets		96
Notes receivable - officers, employees, affiliates, current portion		19
Accounts payable and accrued liabilities, current portion		(3,688)
Contract liabilities		(841)
Finance leases - non-current		(134)
Post-retirement obligations, less current portion		(5,782)
Total identifiable assets		3,775
Goodwill		14,414
Net assets acquired		18,189
Project Design Consultants, LLC (“PDC”)
Business Acquisition [Line Items]
Total Purchase Price		14,178	$ 14,200
Purchase Price Allocation:
Accounts Receivable, net		2,199
Contract assets		926
Prepaid and other current assets		161
Property and equipment, net		489
Intangible assets		10,344
Accounts payable and accrued liabilities, current portion		(1,118)
Contract liabilities		(1,362)
Other non-current obligations		(273)
Finance leases - non-current		36
Total identifiable assets		11,402
Goodwill		2,776
Net assets acquired		$ 14,178