Stockholders' Equity - ATM Facility & Share Offering - Additional Information (Detail) - At-the-Market Offering [Member] - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
Jan. 31, 2019	Jun. 30, 2019	Jun. 30, 2019
Class of Stock [Line Items]
Common stock shares maximum aggregate offering price	$ 20,000,000
Stock issuances, sales agent commission maximum percentage	3.00%
Number of shares of common stock sold		0	0

Number of new stock issued during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
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-Section S99
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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 505
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration