Commitments and Contingencies (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) lease	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments and Contingencies [Abstract]
Number of long-term, non-cancelable operating leases \| lease	81
Rent expense	$ 33.6	$ 33.7	$ 37.5
Rent expense (benefit) related to facilities no longer in use	$ 0.3	$ (1.9)

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration