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BUSINESS COMBINATIONS (Acquisitions) (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 28, 2019 | Jul. 02, 2019 | Mar. 08, 2019 | Nov. 09, 2018 | Oct. 01, 2018 | Apr. 30, 2018 | Dec. 27, 2019 | Sep. 27, 2019 | Jun. 28, 2019 | Mar. 29, 2019 | Dec. 28, 2018 | Sep. 28, 2018 | Jun. 29, 2018 | Mar. 30, 2018 | Dec. 27, 2019 | Dec. 28, 2018 | Dec. 29, 2017 | Jun. 26, 2019
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 71,756 | $ 124,344 | $ 14,603 |
Cash paid at closing |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 27,000 |  |  |
Other receivable for working capital adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (63) | (113) |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | $ 127,647 |  |  |  | $ 97,748 |  |  |  | 127,647 | 97,748 | 38,184 |
Additional amortization expense charge due to increase in fair value of intangible assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,600 | 4,500 | 2,400 |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues. |  |  |  |  |  |  | 129,416 | $ 117,494 | $ 104,396 | $ 91,793 | 86,438 | $ 71,386 | $ 59,833 | $ 54,595 | 443,099 | 272,252 | 273,352 |
Income from operations |  |  |  |  |  |  | $ 5,529 | 1,295 | $ 2,773 | $ (234) | $ 1,679 | $ 4,913 | $ 4,205 | $ 1,974 | 9,363 | 12,771 | $ 13,704 |
Delayed Draw Term Loan Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50,000
E3, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax deductible goodwill | $ 22,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Value of shares issued and issuable | $ 5,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of trading days considered for calculation of weighted average price per share prior to closing date | 10 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period over which financial targets must be met | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum Payout | $ 12,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration | 7,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid | 25,217 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other working capital adjustment | 1,973 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration | 39,190 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid at closing | 27,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current assets (1) | 5,316 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current assets (2) | 341 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash | 2,264 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equipment and leasehold improvements, net | 409 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right-of-use asset | 6,766 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current lease liability | (593) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current lease liability | (7,870) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities | (3,138) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | 21,995 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired | 39,190 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues. |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,700 |  |  |
Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,200 |  |  |
E3, Inc. | Other General And Administrative Expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 100 |  |  |
E3, Inc. | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Earn-Out Payments | 12,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration | 44,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
E3, Inc. | Backlog |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets | 2,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
E3, Inc. | Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets | 8,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
E3, Inc. | Tradename |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets | 2,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
E3, Inc. | Non-compete agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets | $ 900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Onsite Energy Corporation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax deductible goodwill |  | $ 6,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid |  | 24,411 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other working capital adjustment |  | 494 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration |  | 24,905 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current assets (1) |  | 22,254 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current assets (2) |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equipment and leasehold improvements, net |  | 39 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right-of-use asset |  | 828 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current lease liability |  | (168) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current lease liability |  | (660) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities |  | (12,222) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  | 6,150 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired |  | 24,905 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in current assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 200 |  |  |
Increase in carrying value of goodwill |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 900 |  |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues. |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,700 |  |  |
Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,800 |  |  |
Onsite Energy Corporation | General and administrative expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 300 |  |  |
Onsite Energy Corporation | Backlog |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  | 800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Onsite Energy Corporation | Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  | 7,374 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Onsite Energy Corporation | Tradename |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  | 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
The Weidt Group |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax deductible goodwill |  |  | $ 11,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid |  |  | 22,136 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration |  |  | 22,136 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current assets (1) |  |  | 2,317 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current assets (2) |  |  | 25 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equipment and leasehold improvements, net |  |  | 198 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right-of-use asset |  |  | 1,730 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current lease liability |  |  | (245) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current lease liability |  |  | (1,533) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities |  |  | (612) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  | 11,546 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired |  |  | 22,136 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in carrying value of backlog, customer relationships, tradename, and developed technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 900 |  |  |
Decrease in carrying value of liabilities and goodwill |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,200 |  |  |
Additional amortization expense charge due to increase in fair value of intangible assets |  |  |  |  |  |  |  | 100 |  |  |  |  |  |  |  |  |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 400 |  |  |
Revenues. |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,400 |  |  |
Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,900 |  |  |
The Weidt Group | Backlog |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 750 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
The Weidt Group | Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 4,240 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
The Weidt Group | Tradename |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  | 550 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
The Weidt Group | Developed technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  | $ 3,170 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lime Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid |  |  |  |  | $ 122,439 |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration |  |  |  | $ 120,000 | 122,439 |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid at closing |  |  |  | $ 56,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current assets (1) |  |  |  |  | 45,401 |  |  |  |  |  |  |  |  |  |  |  |  |
Non-current assets (2) |  |  |  |  | 10,605 |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  | 1,090 |  |  |  |  |  |  |  |  |  |  |  |  |
Equipment and leasehold improvements, net |  |  |  |  | 1,892 |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities |  |  |  |  | (33,603) |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  | 47,744 |  |  |  |  |  |  |  |  |  |  |  |  |
Net assets acquired |  |  |  |  | 122,439 |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in carrying value of backlog, customer relationships, tradename, and developed technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16,200 |  |  |
Increase in carrying value of goodwill |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (16,200) |  |  |
Additional amortization expense charge due to increase in fair value of intangible assets |  |  |  |  |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |
Unaudited pro forma financial information |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pro forma revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 473,655 | 452,082 |  |
Pro forma income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,937 | 19,694 |  |
Pro forma net income |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,161 | $ 11,934 |  |
Earnings per share: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basic (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.55 | $ 1.09 |  |
Diluted (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.52 | $ 1.04 |  |
Weighted average shares outstanding: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basic (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,162 | 10,990 |  |
Diluted (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,766 | 11,489 |  |
Revenue and Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 200 |  |  |
Revenues. |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 158,700 | $ 181,500 |  |
Income from operations |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,500 | $ 8,400 |  |
Lime Energy | Backlog |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 1,300 |  |  |  |  |  |  |  |  |  |  |  |  |
Lime Energy | Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 35,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Lime Energy | Tradename |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | 5,970 |  |  |  |  |  |  |  |  |  |  |  |  |
Lime Energy | Developed technology |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocation of acquired assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets |  |  |  |  | $ 7,040 |  |  |  |  |  |  |  |  |  |  |  |  |
NAM | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration |  |  |  |  |  | $ 4,000 |  |  |  |  |  |  |  |  |  |  |  |
Willdan Energy Solutions | Onsite Energy Corporation | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration for acquisitions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration |  | $ 26,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
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