GOODWILL AND OTHER INTANGIBLE ASSETS - Carrying Value of Goodwill by Reporting Unit (Details)	9 Months Ended
Sep. 29, 2017 USD ($)
Changes in carrying value of goodwill
Goodwill at beginning of period	$ 21,947,000
Additional Purchase Cost	18,109,000
Goodwill at end of period	40,056,000
Energy Efficiency Services
Changes in carrying value of goodwill
Goodwill at beginning of period	21,198,000
Additional Purchase Cost	18,109,000
Goodwill at end of period	39,307,000
Financial Services
Changes in carrying value of goodwill
Goodwill at beginning of period	749,000
Additional Purchase Cost	0
Goodwill at end of period	$ 749,000

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant