Derivative Financial Instruments (Narrative) (Details) - Foreign exchange contracts - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives	$ 95.0	$ 52.1
Cash Flow Hedging \| Derivatives designated as hedging instruments
Derivative [Line Items]
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives	$ 93.5	$ 76.5

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant