Employee Stock Benefit Plans - Restricted Stock Units - General Information (Details) - Restricted stock units	6 Months Ended
Jun. 30, 2017 shares
Employee Stock Benefit Plans
Right to number of shares of common stock per RSU (in shares)	1
Vesting percentage (as a percent)	25.00%

Percentage of vesting of share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration