Goodwill and Identifiable Intangibles (Tables)

12 Months Ended

Dec. 31, 2015

Changes in the net carrying amount of goodwill by segment were as follows:



(in millions of dollars)	ACCO Brands North America			ACCO Brands International			Computer Products Group		Total
(in millions of dollars)	ACCO Brands North America			ACCO Brands International			Computer Products Group		Total
Balance at December 31, 2013	$	393.1		$	168.4		$	6.8	$	568.3
Translation	(5.5		)	(17.9		)	—		(23.4		)
Balance at December 31, 2014	387.6			150.5			6.8		544.9
Translation	(10.1		)	(37.9		)	—		(48.0		)
Balance at December 31, 2015	$	377.5		$	112.6		$	6.8	$	496.9
Goodwill	$	508.4		$	196.8		$	6.8	$	712.0
Accumulated impairment losses	(130.9		)	(84.2		)	—		(215.1		)
Balance at December 31, 2015	$	377.5		$	112.6		$	6.8	$	496.9

The gross carrying value and accumulated amortization by class of identifiable intangible assets as of December 31, 2015 and 2014 were as follows:



	December 31, 2015								December 31, 2014
(in millions of dollars)	Gross Carrying Amounts		Accumulated Amortization				Net Book Value		Gross Carrying Amounts		Accumulated Amortization				Net Book Value
Indefinite-lived intangible assets:
Trade names	$	471.8	$	(44.5	)	⁽¹⁾	$	427.3	$	499.4	$	(44.5	)	⁽¹⁾	$	454.9
Amortizable intangible assets:
Trade names	122.6		(61.7		)		60.9		127.7		(55.5		)		72.2
Customer and contractual relationships	94.9		(63.1		)		31.8		100.4		(57.2		)		43.2
Patents/proprietary technology	0.9		—				0.9		10.2		(9.1		)		1.1
Subtotal	218.4		(124.8		)		93.6		238.3		(121.8		)		116.5
Total identifiable intangibles	$	690.2	$	(169.3	)		$	520.9	$	737.7	$	(166.3	)		$	571.4


(1)	Accumulated amortization prior to the adoption of authoritative guidance on goodwill and other intangible assets, at which time further amortization ceased.

Estimated amortization expense for amortizable intangible assets for the next five years is as follows:



(in millions of dollars)	2016		2017		2018		2019		2020
Estimated amortization expense	$	17.5	$	14.3	$	12.1	$	9.9	$	7.8