INTANGIBLE ASSETS, NET (Tables)

3 Months Ended

Mar. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of Intangible Assets by Major Class

The following tables summarize the gross carrying amounts and accumulated amortization of intangible assets by major class:
	March 31, 2021
	Gross		Accumulated Amortization		Net
	(thousands of dollars)
Customer relationships	$	16,852	$	(7,302)	$	9,550
Non-compete agreements	94		(94)		—
Licenses and permits	1,471		(734)		737
Developed technology	6,131		(3,985)		2,146
Total	$	24,548	$	(12,115)	$	12,433

	December 31, 2020
	Gross		Accumulated Amortization		Net
	(thousands of dollars)
Customer relationships	$	16,852	$	(7,022)	$	9,830
Non-compete agreements	94		(94)		—
Licenses and permits	1,471		(707)		764
Developed technology	6,131		(3,832)		2,299
Total	$	24,548	$	(11,655)	$	12,893

Estimated Amortization Expenses for Succeeding Five Fiscal Years

Based on identified intangible assets that are subject to amortization as of March 31, 2021, we expect future amortization expenses for each period to be as follows:

	Total		Remainder of 2021		2022		2023		2024		2025		2026		Thereafter
	(thousands of dollars)
Customer relationships	$	9,550	$	843	$	1,123	$	1,123	1,123		1,123		1,123		$	3,092
Licenses and permits	737		74		86		86		86		86		86		233
Developed technology	2,146		460		613		613		460		—		—		—
Total future amortization expense	$	12,433	$	1,377	$	1,822	$	1,822	$	1,669	$	1,209	$	1,209	$	3,325