Intangible Assets, net

12 Months Ended

Dec. 31, 2021

Intangible Assets, net

Intangible Assets, net

10. Intangible Assets, net

Intangible assets include customer relationships and contracts associated with various business and asset acquisitions. These acquired intangible assets were recorded at fair value determined as of the acquisition date and are being amortized over the period we expect to benefit from the assets. Intangible assets, net consisted of the following:

	December 31, 2021				December 31, 2020
	Gross				Gross
	Carrying		Accumulated		Carrying		Accumulated
(in thousands)	Amount		Amortization		Amount		Amortization
Customer-related (15 ― 25 year life)	$	144,322	$	(96,435)	$	147,169	$	(86,512)
Contract-based (5 ― 7 year life)		—		—		37,730		(36,856)
Intangible assets	$	144,322	$	(96,435)	$	184,899	$	(123,368)

Amortization expense of these intangible assets totaled $11.3 million, $15.6 million and $15.3 million during the years ended December 31, 2021, 2020 and 2019, respectively.

Estimated future intangible assets amortization expense as of December 31, 2021 was as follows:

(in thousands)
2022	$	8,913
2023		7,060
2024		5,895
2025		3,763
2026		3,179
Thereafter		19,077
Total	$	47,887