Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Cash Flows [Abstract]
Cash of discontinued operations	$ 0.0	$ 0.0	$ 31.9	$ 16.5

Amount of currency on hand, demand deposits with banks or financial institutions, and other kinds of accounts that have the general characteristics of demand deposits, held by a disposal group.

No definition available.

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant