Intangible Assets

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

The gross carrying amount and accumulated amortization for intangible assets consisted of the following ($ in millions):



	June 30, 2019
	Gross Carrying Amount		Accumulated Amortization		Accumulated Impairments		Accumulated Foreign Exchange			Net Carrying Amount
Amortized Intangible Assets (Advanced Materials & Structures)
Customer relationships	$	276.3	$	59.1	$	—	$	0.9		$	216.3
Developed technology	34.0		9.7		—		0.3			24.0
Trade names	21.8		0.8		20.7		0.3			—
Non-compete agreements	2.9		2.0		—		—			0.9
Patents	1.5		0.4		—		—			1.1
Total	$	336.5	$	72.0	$	20.7	$	1.5		$	242.3

Unamortized Intangible Assets (Advanced Materials & Structures)
Trade names	$	20.0	$	—	$	0.1	$	(0.1	)	$	20.0



	December 31, 2018
	Gross Carrying Amount		Accumulated Amortization		Accumulated Impairments		Accumulated Foreign Exchange			Net Carrying Amount
Amortized Intangible Assets (Advanced Materials & Structures)
Customer relationships	$	276.3	$	50.4	$	—	$	0.7		$	225.2
Developed technology	34.0		8.5		—		0.2			25.3
Trade names	21.8		0.8		20.7		0.3			—
Non-compete agreements	2.9		1.7		—		—			1.2
Patents	1.5		0.4		—		—			1.1
Total	$	336.5	$	61.8	$	20.7	$	1.2		$	252.8

Unamortized Intangible Assets (Advanced Materials & Structures)
Trade names	$	20.0	$	—	$	0.1	$	(0.1	)	$	20.0

Amortization expense of intangible assets was $5.1 million and $5.2 million for the three months ended June 30, 2019 and 2018, respectively, and $10.2 million and $10.4 million for the six months ended June 30, 2019 and 2018, respectively. Finite-lived intangibles in the AMS segment are expensed using the straight-line amortization method. The estimated average aggregate amortization expense is $19.9 million in each of the next five years.