New accounting standards ASU 2018-02 (Details 3) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Adjustments for New Accounting Pronouncement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of certain prior period tax effects from accumulated other comprehensive loss	$ (7.9)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration