9. OTHER INTANGIBLE ASSETS, NET

Intangible assets are generally the result of acquisitions and consist primarily of purchased technology, customer related intangibles, and trademarks. Intangible assets are amortized over useful lives that generally range between 1 and 20 years.

The following tables present the cumulative composition of the Corporation’s intangible assets as of December 31, 2018 and December 31, 2017, respectively.



	2018							2017
(In thousands)	Gross		Accumulated Amortization			Net		Gross		Accumulated Amortization			Net
Technology	$	238,212	$	(123,156	)	$	115,056	$	243,440	$	(114,036	)	$	129,404
Customer related intangibles	358,832		(193,455		)	165,377		367,230		(180,580		)	186,650
Programs ⁽¹⁾	144,000		(5,400		)	138,600		—		—			—
Other intangible assets	40,340		(29,806		)	10,534		40,640		(27,026		)	13,614
Total	$	781,384	$	(351,817	)	$	429,567	$	651,310	$	(321,642	)	$	329,668

⁽¹⁾ Programs include values assigned to major programs of acquired businesses and represent the aggregate value associated with the customer relationships, contracts, technology, and trademarks underlying the associated program.

During the year ended December 31, 2018, the Corporation acquired intangible assets of $146.1 million which included Programs of $144.0 million, Customer-related intangibles of $1.8 million, and Other intangible assets of $0.3 million. The weighted average amortization periods for these aforementioned intangible assets are 20.0 years, 10.4 years, and 8.0 years, respectively.

Amortization expense from continuing operations for the years ended December 31, 2018, 2017, and 2016 was $43.6 million, $38.4 million, and $33.4 million, respectively. The estimated future amortization expense of intangible assets over the next five years is as follows:



(In thousands)
2019	$	43,488
2020	41,576
2021	39,826
2022	37,312
2023	33,641