Cash and cash equivalents (Details) - EUR (€)	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Jun. 30, 2017	Jan. 01, 2017
Cash and cash equivalents
Cash	€ 571,040,000		€ 620,145,000
Securities and time deposits	1,086,421,000		357,964,000
Cash and cash equivalents	1,657,461,000	€ 978,109,000	978,109,000	€ 720,982,000	€ 708,882,000
Restricted cash	€ 984,000		€ 53,694,000

The amount of cash on hand and demand deposits. [Refer: Cash on hand]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References

No definition available.

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The amount of short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value.

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- Definition

The amount of cash and cash equivalents whose use or withdrawal is restricted. [Refer: Cash and cash equivalents]

+ References

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