8.	OTHER INTANGIBLE ASSETS

Other intangible assets consisted of the following:


December 31, 2018	Gross Cost		Accumulated Amortization			Net Cost
Technologies & licences		705		(592	)		113
Purchased & internally developed software		459		(404	)		55
Construction in progress		44		—			44
Other intangible assets		69		(69	)		—

Total		1,277		(1,065	)		212


December 31, 2017	Gross Cost		Accumulated Amortization			Net Cost
Technologies & licences		668		(566	)		102
Purchased & internally developed software		440		(383	)		57
Construction in progress		50		—			50
Other intangible assets		70		(70	)		—

Total		1,228		(1,019	)		209

The line “Construction in progress” in the table above includes internally developed software under construction and software not ready for use.

The amortization expense in 2018, 2017 and 2016 was $64 million, $58 million and $61 million, respectively.

The estimated amortization expense of the existing intangible assets for the following years is:


Year
2019			77
2020			60
2021			40
2022			23
2023			8
Thereafter			4

Total			212

In 2018, the Company impaired $2 million of acquired technologies for which it was determined that they had no alternative future use.

In 2017, there was no impairment of intangible assets, while in 2016, the Company impaired $4 million of acquired technologies for which it was determined that they had no alternative future use.