Fair Value Measurements - Additional Information (Details) - shares	Jun. 30, 2019	Dec. 31, 2018
Class Of Warrant Or Right [Line Items]
Warrants outstanding	57,722,416	65,685,269
Febuary 2018 Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrants outstanding	125,000

Number of warrants or rights outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant