We account for goodwill and other intangible assets in accordance with the provisions of ASC 350 and account for business combinations using the acquisition method of accounting and accordingly, the assets and liabilities of the entities acquired are recorded at their estimated fair values at the acquisition date. Goodwill is the excess of purchase price over the fair value of tangible and identifiable intangible net assets acquired in various business combinations. Goodwill is not amortized but is tested for impairment annually at the reporting unit level, or more often if indications of impairment exist. We assess the fair value of reporting units on a non-recurring basis using a combination of two valuation methods, a market approach and an income approach, to estimate the fair value of our reporting units. The implied fair value of our reporting units is determined based on significant unobservable inputs; accordingly, these inputs fall within Level 3 of the fair value hierarchy.

Our reporting units are the Adhesive Dispensing Systems segment, the Industrial Coating Systems segment and one level below the Advanced Technology Systems segment.

In the fourth quarter of each year, we estimate a reporting unit’s fair value using a combination of the discounted cash flow method of the Income Approach and the guideline public company method of the Market Approach and compare the result against the reporting unit’s carrying value of net assets. An impairment charge is recorded for the amount by which the carrying value of the reporting unit exceeds the fair value of the reporting unit, as calculated in the quantitative analysis described above. We did not record any goodwill impairment charges in 2018, 2017, or 2016.

	Adhesive Dispensing Systems			Advanced Technology Systems			Industrial Coating Systems		Total
Balance at October 31, 2017	$	392,295		$	1,172,857		$	24,058	$	1,589,210
Acquisitions		—			24,679			—		24,679
Currency effect		(3,304	)		(2,567	)		—		(5,871	)
Balance at October 31, 2018	$	388,991		$	1,194,969		$	24,058	$	1,608,018

	Adhesive Dispensing Systems		Advanced Technology Systems		Industrial Coating Systems		Total
Balance at October 31, 2016	$	385,733	$	697,346	$	24,058	$	1,107,137
Acquisition		—		470,248		—		470,248
Currency effect		6,562		5,263		—		11,825
Balance at October 31, 2017	$	392,295	$	1,172,857	$	24,058	$	1,589,210

Accumulated impairment losses, which were recorded in 2009, were $232,789 at October 31, 2018 and October 31, 2017. Of these losses, $229,173 related to the Advanced Technology Systems segment and $3,616 related to the Industrial Coating Systems segment.

	October 31, 2018
	Carrying Amount		Accumulated Amortization		Net Book Value
Customer relationships	$	480,404	$	137,640	$	342,764
Patent/technology costs		153,602		59,845		93,757
Trade name		96,433		34,768		61,665
Noncompete agreements		11,469		9,919		1,550
Other		1,386		1,381		5
Total	$	743,294	$	243,553	$	499,741

	October 31, 2017
	Carrying Amount		Accumulated Amortization		Net Book Value
Customer relationships	$	480,536	$	102,033	$	378,503
Patent/technology costs		150,581		48,669		101,912
Trade name		93,281		28,366		64,915
Noncompete agreements		11,142		9,298		1,844
Other		1,384		1,378		6
Total	$	736,924	$	189,744	$	547,180

Amortization expense for 2018, 2017 and 2016 was $55,448, $44,907 and $29,061 respectively.