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.

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

Commitments, Contingencies and Guarantees (Details) € in Millions, $ in Millions	Apr. 29, 2019 lawsuit	Dec. 31, 2018 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 USD ($)
Loss Contingencies [Line Items]
Amount of fine		€ 3.0	$ 3.4	€ 3.3	$ 3.9	€ 5.0	$ 5.4
ProShares Trust II Securities Litigation, No. 19-cv-886-DLC
Loss Contingencies [Line Items]
Number of lawsuits consolidated	3