Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities	$ 585	$ 2,081

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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration