Derivative Instruments, Foreign Exchange Contracts (Details) - EUR (€) € in Millions	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Derivative [Abstract]
Expiration date of contract	Dec. 31, 2020
Foreign Exchange Contracts [Member]
Derivative [Abstract]
Foreign exchange contract outstanding	€ 3.2	€ 3.2

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