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SEGMENT AND GEOGRAPHICAL INFORMATION - Concentration Risk (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Oct. 01, 2021	Sep. 30, 2022	Oct. 01, 2021
Geographic Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | CALIFORNIA
Concentration Risk [Line Items]
Concentration risk percentage	37.20%	38.90%	40.30%	36.20%
Geographic Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | NEW YORK
Concentration Risk [Line Items]
Concentration risk percentage	23.40%	19.00%	21.40%	20.70%
Top Ten Customers, Three Months Ended 2022 September 30 | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage	57.20%
Top Ten Customers, Nine Months Ended 2022 September 30 | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage			54.50%
Top Ten Customers, Three Months Ended 2021 October 01 | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage		52.40%
Top Ten Customers, Nine Months Ended 2021 October 01 | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage				46.80%
Pueblo County School District | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage		13.30%
Los Angeles Department of Water and Power | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Concentration risk percentage		17.00%	13.20%
Los Angeles Department of Water and Power | Customer Concentration Risk [Member] | Revenue from Contract with Customer, Segment Benchmark [Member] | Energy
Concentration Risk [Line Items]
Concentration risk percentage		20.40%
Pueblo County School District, Dormitory Authority State of New York, and Los Angeles Department of Water and Power | Customer Concentration Risk [Member] | Revenue from Contract with Customer, Segment Benchmark [Member] | Energy
Concentration Risk [Line Items]
Concentration risk percentage	38.30%
Los Angeles Department of Water and Power and Pueblo County School District | Customer Concentration Risk [Member] | Revenue from Contract with Customer, Segment Benchmark [Member] | Energy
Concentration Risk [Line Items]
Concentration risk percentage			26.50%
Los Angeles Department of Water and Power and Consolidated Edison of New York | Customer Concentration Risk [Member] | Revenue from Contract with Customer, Segment Benchmark [Member] | Energy
Concentration Risk [Line Items]
Concentration risk percentage				21.50%
City of Elk Grove | Customer Concentration Risk [Member] | Revenue from Contract with Customer, Segment Benchmark [Member] | Engineering and Consulting
Concentration Risk [Line Items]
Concentration risk percentage				12.20%

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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-Publisher FASB
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