GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS - NARRATIVE (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 706,960,000	$ 706,960,000	$ 702,070,000
Goodwill impairment	0	0	0
Impairment of intangible assets	0	0	4,800,000
Amortization expense	5,900,000	5,400,000	6,100,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | MTF and ACB
Goodwill [Line Items]
Goodwill impairment			$ 3,600,000
ETG Utility Operations
Goodwill [Line Items]
Goodwill	700,200,000	700,200,000
Corporate Services and Other Operations
Goodwill [Line Items]
Goodwill	$ 6,800,000	$ 6,800,000
Minimum
Goodwill [Line Items]
Useful life of finite-lived intangible assets (in years)	2 years
Maximum
Goodwill [Line Items]
Useful life of finite-lived intangible assets (in years)	20 years