REVENUE RECOGNITION AND CONTRACTS - B&W Environmental Loss Contracts (Details) - B&W Environmental segment	3 Months Ended
	Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Number of contracts in a loss position | contract	2
Renewable loss contracts, net gain (loss) recognized on changes in estimated revenues and costs | $	$ 0	$ 0
First SPIG Contract
Disaggregation of Revenue [Line Items]
Percent complete	100.00%
Second SPIG Contract
Disaggregation of Revenue [Line Items]
Percent complete	99.00%