RECEIVABLES - Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2018		Jan. 01, 2018	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Trade accounts receivable	$ 207,266				$ 244,133
Unbilled revenues	76,268				69,138
Allowance for doubtful accounts	(15,182)				(11,308)	$ (7,835)	$ (3,548)
Total	$ 268,352	[1]	$ 301,963		$ 301,963

[1] Includes billed and unbilled amounts, net of allowance for doubtful accounts. See Note 4 for details.