Intangible Assets and Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Carrying amount of intangible assets

The following table summarizes the carrying amount of intangible assets as of December 31, 2017 and 2016:

	As of December 31,
	2017			2016
	(Dollars in millions)
Acquired contractual rights(1)	$	81.4		$	74.1
Acquired trademarks(1)	1.2			1.0
Accumulated amortization	(57.8		)	(43.2		)
Finite-lived intangible assets, net	24.8			31.9
Goodwill(1)	11.1			10.1
Intangible assets, net	$	35.9		$	42.0

(1) Changes in the carrying amounts of acquired contractual rights, acquired trademarks, and goodwill are due to foreign currency translation.

Summary of estimated amortization expense, excluding impairment losses

The following table summarizes the expected amortization expense for 2018 through 2022 and thereafter (Dollars in millions):

2018	$	9.8
2019	6.0
2020	6.0
2021	3.0
	$	24.8