Net Income (Loss) Per Common Share - Schedule of Potential Dilutive Common Shares (Detail)	12 Months Ended
	Dec. 31, 2017 shares
Minimum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	519,963,713
Minimum [Member] | Series A Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	10,065,629
Minimum [Member] | Series B Redeemable Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	444,444,444
Maximum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	596,693,873
Maximum [Member] | Series A Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	10,065,629
Maximum [Member] | Series B Conversion Per Share Below 2.25 [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	1,015,874
Maximum [Member] | Series B Redeemable Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	444,444,444
Maximum [Member] | Series B Preferred Stock Dividends [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	64,285,714
Maximum [Member] | Series B Preferred Stock Acquisition Conversion Payment [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	11,428,572
Restricted Shares Subject to Vesting [Member] | Minimum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	4,053,640
Restricted Shares Subject to Vesting [Member] | Maximum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	4,053,640
Warrants Outstanding [Member] | Minimum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	61,400,000
Warrants Outstanding [Member] | Maximum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive shares if converted to common	61,400,000