Related Parties - Additional Information (Details) - Related Parties - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Treasury Stock
Related Party Transaction [Line Items]
Stock buyback program fees	$ 19	$ 36
Common Class A
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners (more than)	10.00%

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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration