SEGMENT INFORMATION - Revenue and Gross Margin by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue and other financial information by reportable segment
Revenue	$ 213,668	$ 195,166	$ 626,697	$ 586,212
Gross margin	106,141	103,234	315,966	318,255
Contract Operations
Revenue and other financial information by reportable segment
Revenue	170,497	158,911	500,451	488,810
Gross margin	98,803	97,631	295,901	304,778
Aftermarket Services
Revenue and other financial information by reportable segment
Revenue	43,171	36,255	126,246	97,402
Gross margin	$ 7,338	$ 5,603	$ 20,065	$ 13,477