Summary of Significant Accounting Policies - Additional Information (Details 2)	12 Months Ended
Dec. 31, 2017 segment
Description of Business
Number or reportable segments	1
Cash and Cash Equivalents
Maturity period of highly liquid investments	3 months

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration