Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

(In millions)	Capacity Agreement			Developed Technology			Total
June 30, 2018
Cost	$	10.1		$	—		$	10.1
Accumulated amortization	(2.8		)	—			(2.8		)
Intangible assets, net	$	7.3		$	—		$	7.3
December 31, 2017
Cost	$	10.1		$	4.3		$	14.4
Accumulated amortization	(1.9		)	(1.6		)	(3.5		)
Impairment charges	—			(2.7		)	$	(2.7	)
Intangible assets, net	$	8.2		$	—		$	8.2

Schedule of Amortization Expense for Intangible Assets

Amortization expense for intangible assets consisted of the following:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In millions)	2018		2017		2018		2017
Amortization expense	$	0.4	$	0.7	$	0.9	$	1.2

Schedule of Intangible Assets Estimated Amortization Expense

Estimated amortization expense for the remainder of 2018 and each of the next four years ending December 31 is as follows:

(In millions)	2018 (Remainder)		2019		2020		2021		2022
Amortization expense	$	1.0	$	2.0	$	2.0	$	2.0	$	0.2