Fair Value Measurements - Additional Information (Detail) - USD ($)		3 Months Ended
	Aug. 03, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Common stock, shares issued			12,350,360	7,201,774
Transfers of assets out of Level 1 into Level 2			$ 0
Transfers of assets out of Level 2 into Level 1			0
Transfers of liabilities out of Level 1 into Level 2			0
Transfers of liabilities out of Level 2 into Level 1			0
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets			0
Liabilities			0
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets			0
Liabilities			$ 0
2016 Financings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Common stock, shares issued	5,048,632	5,048,632
Aggregate gross proceeds from sale of common stock and warrants	$ 14,500,000	$ 14,500,000
2016 Financings [Member] | Maximum [Member] | Common Stock Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants to purchase of common stock		2,975,444
Underwriters [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants to purchase of common stock		252,432