Business Acquisitions - Narrative (Details)								12 Months Ended
	Dec. 20, 2019 USD ($)	Nov. 08, 2019 USD ($)	Jul. 02, 2019 USD ($)	Jul. 01, 2019 USD ($) installments shares	Jun. 03, 2019 USD ($) installments shares	Mar. 22, 2019 USD ($) installments	Dec. 31, 2018 USD ($) installments shares	Dec. 28, 2019 USD ($)	Mar. 28, 2020 USD ($)	Dec. 29, 2018 USD ($)
Business Acquisition [Line Items]
Consideration transfered, excess working capital	$ 8,781,000
Consideration transfered, cash paid at closing	6,677,000
Long-term debt	150,000,000
Line of credit facility, current borrowing capacity	215,000,000.0
Total consideration								$ 369,879,000
Earn-out of cash fair value								4,002,000	$ 3,074,000	$ 4,698,000
Promissory note incurred								1,004,000
AR Credit Agreement
Business Acquisition [Line Items]
Payments to acquire businesses	318,428,000
Line of credit facility, current borrowing capacity	$ 215,000,000
GHD Services, Inc
Business Acquisition [Line Items]
Total consideration		$ 8,300,000
WHPacific, Inc.
Business Acquisition [Line Items]
Total consideration			$ 9,000,000
GeoDesign, Inc
Business Acquisition [Line Items]
Payments to acquire businesses				$ 8,247,000
Total consideration				11,245,000
Consideration transferred of common stock				$ 375,000
Common stock number of shares | shares				4,731
Common stock purchase price				$ 425,000
Earn-out of cash				1,500,000
Earn-out of cash fair value				198,000
GeoDesign, Inc | Uncollateralized promissory notes
Business Acquisition [Line Items]
Notes payable				$ 2,000,000				2,000,000	2,000,000
Promissory note interest rate				4.00%
Number of installments | installments				4
Periodic payment				$ 500,000
Alta Environmental, L.P
Business Acquisition [Line Items]
Payments to acquire businesses					$ 4,000,000
Total consideration					6,323,000
Earn-out of cash					500,000
Earn-out of cash fair value					323,000
Alta Environmental, L.P | Uncollateralized promissory notes
Business Acquisition [Line Items]
Notes payable					$ 2,000,000
Promissory note interest rate					4.00%
Number of installments | installments					4
Periodic payment					$ 500,000
Page One Consultants
Business Acquisition [Line Items]
Payments to acquire businesses					2,293,000
Total consideration					$ 3,995,000
Common stock number of shares | shares					2,647
Common stock purchase price					$ 200,000
Earn-out of cash					500,000
Earn-out of cash fair value					$ 302,000
Page One Consultants | Uncollateralized promissory notes
Business Acquisition [Line Items]
Notes payable								1,000,000	1,000,000
Promissory note interest rate					3.00%
Number of installments | installments					3
Periodic payment					$ 333,000
Promissory note incurred					$ 1,000,000
Acquisition of The Sextant Group
Business Acquisition [Line Items]
Payments to acquire businesses						$ 6,501,000
Total consideration						$ 10,501,000
Acquisition of The Sextant Group | Uncollateralized promissory notes
Business Acquisition [Line Items]
Notes payable								3,140,000	3,000,000
Promissory note interest rate						4.00%
Number of installments | installments						4
Periodic payment						$ 1,000,000
Promissory note incurred						$ 4,000,000
Celtic Energy, Inc
Business Acquisition [Line Items]
Payments to acquire businesses							$ 1,000,000
Total consideration							$ 1,881,000
Common stock number of shares | shares							3,227
Common stock purchase price							$ 200,000
Earn-out of cash							200,000
Earn-out of cash fair value							$ 181,000
Celtic Energy, Inc | Uncollateralized promissory notes
Business Acquisition [Line Items]
Notes payable								$ 300,000	$ 200,000
Promissory note interest rate							3.00%
Number of installments | installments							3
Periodic payment							$ 100,000
Promissory note incurred							$ 300,000