Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02(29))
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Unpaid principal balance of convertible senior note due to related parties		$ 3,000		$ 3,000		$ 3,000
Common stock shares issued	3,549,381
Issuance of common stock public offering	$ 847,400	$ 17,632	$ 31,053	$ 95,585	$ 125,071
Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Common stock shares issued	102,880
Issuance of common stock public offering	$ 25,000