SEGMENT REPORTING - Schedule of Operating Results by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 999,354	$ 847,918	$ 710,873
Eliminations
Segment Reporting Information [Line Items]
Revenues	(21,394)	(10,252)	(592)
B&W Renewable segment | Operating Segments
Segment Reporting Information [Line Items]
Revenues	318,605	288,673	144,310
B&W Renewable segment | B&W Renewable | Operating Segments
Segment Reporting Information [Line Items]
Revenues	165,108	136,376	83,639
B&W Renewable segment | B&W Renewable Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	100,198	78,960	25,852
B&W Renewable segment | Vølund | Operating Segments
Segment Reporting Information [Line Items]
Revenues	53,299	73,337	34,819
B&W Environmental segment | Operating Segments
Segment Reporting Information [Line Items]
Revenues	202,927	154,393	133,826
B&W Environmental segment | B&W Environmental | Operating Segments
Segment Reporting Information [Line Items]
Revenues	97,799	77,863	58,262
B&W Environmental segment | SPIG | Operating Segments
Segment Reporting Information [Line Items]
Revenues	91,132	61,017	55,615
B&W Environmental segment | GMAB | Operating Segments
Segment Reporting Information [Line Items]
Revenues	13,996	15,513	19,949
B&W Thermal segment | Operating Segments
Segment Reporting Information [Line Items]
Revenues	499,216	415,104	433,329
B&W Thermal segment | B&W Thermal | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 499,216	$ 415,104	$ 433,329