RESTRUCTURING ACTIVITIES - Summary of Restructuring Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring activities	$ 4,222	$ 560	$ 4,869
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring activities	2,792	(353)	4,039
Other
Restructuring Cost and Reserve [Line Items]
Restructuring activities	1,430	913	830
Operating Segments | B&W Renewable segment
Restructuring Cost and Reserve [Line Items]
Restructuring activities	2,153	900	1,876
Operating Segments | B&W Renewable segment | Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring activities	1,831	719	1,732
Operating Segments | B&W Renewable segment | Other
Restructuring Cost and Reserve [Line Items]
Restructuring activities	322	181	144
Operating Segments | B&W Environmental segment
Restructuring Cost and Reserve [Line Items]
Restructuring activities	449	228	430
Operating Segments | B&W Environmental segment | Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring activities	180	28	360
Operating Segments | B&W Environmental segment | Other
Restructuring Cost and Reserve [Line Items]
Restructuring activities	269	200	70
Operating Segments | B&W Thermal segment
Restructuring Cost and Reserve [Line Items]
Restructuring activities	1,614	589	2,207
Operating Segments | B&W Thermal segment | Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring activities	781	128	1,734
Operating Segments | B&W Thermal segment | Other
Restructuring Cost and Reserve [Line Items]
Restructuring activities	833	461	473
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring activities	6	(1,157)	356
Corporate | Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring activities	0	(1,228)	213
Corporate | Other
Restructuring Cost and Reserve [Line Items]
Restructuring activities	$ 6	$ 71	$ 143