Derivative Financial Instruments Derivative Financial Instruments (Schedule of Net Investment Hedges) (Details) - EUR (€) € in Millions	Jun. 30, 2018	Dec. 31, 2017
Foreign Currency Denominated Debt [Member] \| Net Investment Hedging [Member]
Derivative [Line Items]
Notional Amount of Nonderivative Instruments	€ 1,050	€ 1,050

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.

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