Note 7. Goodwill

The following table analyzes goodwill movement for 2018 and 2017.


(in millions)	Fuel Specialties		Performance Chemicals			Oilfield Services		Octane Additives			Total
At December 31, 2016
Gross cost ⁽¹⁾	$	207.9	$	129.6		$	37.3	$	236.5		$	611.3
Accumulated impairment losses		0.0		0.0			0.0		(236.5	)		(236.5	)

Net book amount	$	207.9	$	129.6		$	37.3	$	0.0		$	374.8

Exchange effect		0.0		10.2			0.0		0.0			10.2
Measurement period adjustment		0.0		(23.1	)		0.0		0.0			(23.1	)
At December 31, 2017
Gross cost ⁽¹⁾	$	207.9	$	116.6		$	37.3	$	236.5		$	598.3
Accumulated impairment losses		0.0		0.0			0.0		(236.5	)		(236.5	)

Net book amount	$	207.9	$	116.6		$	37.3	$	0.0		$	361.8

Exchange effect		0.0		(4.4	)		0.0		0.0			(4.4	)
Acquisition		0.0		0.0			7.5		0.0			7.5
At December 31, 2018
Gross cost ⁽¹⁾	$	207.9	$	112.2		$	44.8	$	236.5		$	601.4
Accumulated impairment losses		0.0		0.0			0.0		(236.5	)		(236.5	)

Net book amount	$	207.9	$	112.2		$	44.8	$	0.0		$	364.9

(1)	Gross cost is net of $8.7 million, $0.3 million and $289.5 million of historical accumulated amortization in respect of the Fuel Specialties, Performance Chemicals and Octane Additives reporting segments, respectively.

For information regarding the acquisition in 2018 as shown above, see Note 4 of the Notes to the Consolidated Financial Statements.

The Company’s reporting units, the level at which goodwill is tested for impairment, are consistent with the reportable segments: Fuel Specialties, Performance Chemicals, Oilfield Services and Octane Additives. The components in each segment (including products, markets and competitors) have similar economic characteristics and the segments, therefore, reflect the lowest level at which operations and cash flows can be clearly distinguished, operationally and for financial reporting purposes, from the rest of the Company.

The Company assesses goodwill for impairment on at least an annual basis, initially based on a qualitative assessment to determine whether it is more likely than not that the fair value of a segment is less than the carrying amount. If a potential impairment is identified then a two-step impairment test is followed.

The Company performed its annual impairment assessment in respect of goodwill as at December 31, 2018, 2017 and 2016. Our impairment assessment concluded that there had been no impairment of goodwill in respect of those reporting units.

We believe that where appropriate the assumptions used in our impairment assessments are reasonable, but that they are judgmental, and variations in any of the assumptions may result in materially different calculations of any potential impairment charges.