Marketable Securities and Fair Value Measurements Additional Information (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Maturity Period Used To Classify Investments	7 months	7 months
Maximum
Schedule of Available-for-sale Securities [Line Items]
Maturity Period Used To Classify Investments	27 months

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