New Accounting Standards (Tables)

3 Months Ended

Mar. 31, 2019

Accounting Changes And Error Corrections [Abstract]

Summary of Impact of Adoption of New Accounting Standards

Balance Sheet (Dollars in millions)	Balance at December 31, 2018		Adjustments due to ASU 2016-02		Balance at January 1, 2019
Assets
Right-of-use asset, operating leases	$	—	$	155.4	$	155.4
Current liabilities
Operating lease liabilities - current		—		38.7		38.7
Non-current liabilities
Operating lease liabilities - non-current		—		116.7		116.7