Note 7. Goodwill

The following table analyzes goodwill movement for 2017 and 2016.


(in millions)	Fuel Specialties		Performance Chemicals			Oilfield Services		Octane Additives			Total
At December 31, 2015
Gross cost ⁽¹⁾	$	207.9	$	22.2		$	37.3	$	236.5		$	503.9
Accumulated impairment losses		0.0		0.0			0.0		(236.5	)		(236.5	)

Net book amount	$	207.9	$	22.2		$	37.3	$	0.0		$	267.4

Additions		0.0		107.4			0.0		0.0			107.4
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

(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.

During the year we have reviewed the fair values of assets acquired and liabilities assumed for our Huntsman acquisition within our Performance Chemicals segment, based on information becoming available after our previous filing, resulting in a $23.1 million increase in assets acquired and a corresponding decrease in goodwill.

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, 2017, 2016 and 2015. 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.