Segment Information - Narrative (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
GBAM Fund
Segment Reporting Information [Line Items]
Investment amount	$ 2.4

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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Period Type:	duration